Merge branch 'develop'

Build/MQTTnet.Extensions.ManagedClient.nuspec

@@ -34,10 +34,9 @@
     <!-- .NET Framework -->
     <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\net452\MQTTnet.Extensions.ManagedClient.*" target="lib\net452\"/>
 
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net461\"/>
+    <!-- .NET Framework 4.6.0 will use binaries from 4.5.2. -->
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net462\"/>
+    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\net461\MQTTnet.Extensions.Rpc.*" target="lib\net461\"/>
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net470\"/>
+
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net471\"/>
+    <!-- Everything above .NET Framework 4.6.1 will use the binaries from 4.6.1. -->
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net472\"/>
   </files>
 </package>

Build/MQTTnet.Extensions.Rpc.nuspec

@@ -34,10 +34,9 @@
     <!-- .NET Framework -->
     <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\net452\MQTTnet.Extensions.Rpc.*" target="lib\net452\"/>
 
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net461\"/>
+    <!-- .NET Framework 4.6.0 will use binaries from 4.5.2. -->
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net462\"/>
+    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\net461\MQTTnet.Extensions.Rpc.*" target="lib\net461\"/>
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net470\"/>
+
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net471\"/>
+    <!-- Everything above .NET Framework 4.6.1 will use the binaries from 4.6.1. -->
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net472\"/>
   </files>
 </package>

Build/MQTTnet.nuspec

@@ -11,36 +11,12 @@
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker).</description>
     <releaseNotes>
-* [Core] Added support for MQTTv5 packages.
+* [Core] Fixed missing properties from PUBLISH packet in _MqttApplicationMessage_ (thanks to @pcbing).
-* [Core] Performance improvements.
+* [Core] Fixed wrong encoding of PUBREL and PUBCOMP packets for MQTTv5 (thanks to @perphilipp).
-* [Core] Removed obsolete methods.
+* [Client] Added the authentication result to the disconnected handler (only set when connecting failed).
-* [Core] Fixed a memory leak when processing lots of messages (thanks to @tschanko)
+* [Client] Added new overloads for _MqttClientOptionsBuilder_.
-* [Core] Added more overloads for MQTT factory.
+* [Server] Fixed a bug which returns wrong flag for existing session in CONNACK packet (thanks to @avengerstark).
-* [Core] The client password is now hidden from the logs (replaced with **** if set).
+* [nuget] .NET Framework builds are now using 4.5.2 or 4.6.1 builds instead of netstandard 2.0.
-* [Core] Fixed a memory leak when using SSL connections (thanks to @biovoid). 
-* [Client] Added validation of topics before publishing.
-* [Client] Added new MQTTv5 features to options builder.
-* [Client] Added uniform API across all supported MQTT versions (BREAKING CHANGE!)
-* [Client] The client will now avoid sending an ACK if an exception has been thrown in message handler (thanks to @ramonsmits).
-* [Client] Fixed issues in QoS 2 handling which leads to message loss.
-* [Client] Replaced all events with proper async compatible handlers (BREAKING CHANGE!).
-* [Client] Added more configuration values to TCP endpoint options.
-* [Client] Added used PacketIdentifier to publish result.
-* [ManagedClient] Replaced all events with proper async compatible handlers (BREAKING CHANGE!).
-* [ManagedClient] The log ID is now propagated to the internal client (thanks to @vbBerni).
-* [ManagedClient] Added validation of topics before publishing.
-* [ManagedClient] The internal MQTT client is now closed properly (thanks to @vbBerni).
-* [Server] Added support for MQTTv5 clients. The server will still return _success_ for all cases at the moment even if more granular codes are available.
-* [Server] Fixed issues in QoS 2 handling which leads to message loss.
-* [Server] Replaced all events with proper async compatible handlers (BREAKING CHANGE!).
-* [Server] The used logger instance is now propagated to the WebSocket server adapter.
-* [Server] Added the flag "IsSecureConnection" which is set to true when the connection is encrypted.
-* [Server] Fixed wrong will message behavior when stopping server (thanks to @JohBa)
-* [Server] Added validation of topics before publishing.
-* [Server] Added more configuration values to TCP endpoint options.
-* [MQTTnet Server] Added as first Alpha version of standalone cross platform MQTT server.
-
-* [Note] Due to MQTTv5 a lot of new classes were introduced. This required adding new namespaces as well. Most classes are backward compatible but new namespaces must be added.
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2019</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
@@ -60,10 +36,6 @@
       <group targetFramework="uap10.0">
         <dependency id="Microsoft.NETCore.UniversalWindowsPlatform" version="6.2.8" />
       </group>
-      <group targetFramework="net452">
-      </group>
-      <group targetFramework="net461">
-      </group>
     </dependencies>
   </metadata>
 
@@ -83,10 +55,9 @@
     <!-- .NET Framework -->
     <file src="..\Source\MQTTnet\bin\Release\net452\MQTTnet.*" target="lib\net452\"/>
 
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net461\"/>
+    <!-- .NET Framework 4.6.0 will use binaries from 4.5.2. -->
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net462\"/>
+    <file src="..\Source\MQTTnet\bin\Release\net461\MQTTnet.*" target="lib\net461\"/>
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net470\"/>
+
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net471\"/>
+    <!-- Everything above .NET Framework 4.6.1 will use the binaries from 4.6.1. -->
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net472\"/>
   </files>
 </package>

Source/MQTTnet/Client/Disconnecting/MqttClientDisconnectedEventArgs.cs

@@ -1,17 +1,21 @@
 using System;
+using MQTTnet.Client.Connecting;
 
 namespace MQTTnet.Client.Disconnecting
 {
     public class MqttClientDisconnectedEventArgs : EventArgs
     {
-        public MqttClientDisconnectedEventArgs(bool clientWasConnected, Exception exception)
+        public MqttClientDisconnectedEventArgs(bool clientWasConnected, Exception exception, MqttClientAuthenticateResult authenticateResult)
         {
             ClientWasConnected = clientWasConnected;
             Exception = exception;
+            AuthenticateResult = authenticateResult;
         }
 
         public bool ClientWasConnected { get; }
 
         public Exception Exception { get; }
+
+        public MqttClientAuthenticateResult AuthenticateResult { get; }
     }
 }

Source/MQTTnet/Client/MqttClient.cs

@@ -61,6 +61,8 @@ namespace MQTTnet.Client
 
             ThrowIfConnected("It is not allowed to connect with a server after the connection is established.");
 
+            MqttClientAuthenticateResult authenticateResult = null;
+
             try
             {
                 Options = options;
@@ -81,7 +83,7 @@ namespace MQTTnet.Client
 
                 _packetReceiverTask = Task.Run(() => TryReceivePacketsAsync(backgroundCancellationToken), backgroundCancellationToken);
 
-                var authenticateResult = await AuthenticateAsync(adapter, options.WillMessage, cancellationToken).ConfigureAwait(false);
+                authenticateResult = await AuthenticateAsync(adapter, options.WillMessage, cancellationToken).ConfigureAwait(false);
 
                 _sendTracker.Restart();
 
@@ -108,7 +110,7 @@ namespace MQTTnet.Client
 
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(null, exception).ConfigureAwait(false);
+                    await DisconnectInternalAsync(null, exception, authenticateResult).ConfigureAwait(false);
                 }
 
                 throw;
@@ -131,7 +133,7 @@ namespace MQTTnet.Client
             {
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(null, null).ConfigureAwait(false);
+                    await DisconnectInternalAsync(null, null, null).ConfigureAwait(false);
                 }
             }
         }
@@ -232,7 +234,7 @@ namespace MQTTnet.Client
             if (IsConnected) throw new MqttProtocolViolationException(message);
         }
 
-        private async Task DisconnectInternalAsync(Task sender, Exception exception)
+        private async Task DisconnectInternalAsync(Task sender, Exception exception, MqttClientAuthenticateResult authenticateResult)
         {
             var clientWasConnected = IsConnected;
 
@@ -267,7 +269,7 @@ namespace MQTTnet.Client
                 var disconnectedHandler = DisconnectedHandler;
                 if (disconnectedHandler != null)
                 {
-                    await disconnectedHandler.HandleDisconnectedAsync(new MqttClientDisconnectedEventArgs(clientWasConnected, exception)).ConfigureAwait(false);
+                    await disconnectedHandler.HandleDisconnectedAsync(new MqttClientDisconnectedEventArgs(clientWasConnected, exception, authenticateResult)).ConfigureAwait(false);
                 }
             }
         }
@@ -376,7 +378,7 @@ namespace MQTTnet.Client
 
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(_keepAlivePacketsSenderTask, exception).ConfigureAwait(false);
+                    await DisconnectInternalAsync(_keepAlivePacketsSenderTask, exception, null).ConfigureAwait(false);
                 }
             }
             finally
@@ -404,7 +406,7 @@ namespace MQTTnet.Client
                     {
                         if (!DisconnectIsPending())
                         {
-                            await DisconnectInternalAsync(_packetReceiverTask, null).ConfigureAwait(false);
+                            await DisconnectInternalAsync(_packetReceiverTask, null, null).ConfigureAwait(false);
                         }
 
                         return;
@@ -436,7 +438,7 @@ namespace MQTTnet.Client
 
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(_packetReceiverTask, exception).ConfigureAwait(false);
+                    await DisconnectInternalAsync(_packetReceiverTask, exception, null).ConfigureAwait(false);
                 }
             }
             finally
@@ -497,7 +499,7 @@ namespace MQTTnet.Client
 
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(_packetReceiverTask, exception).ConfigureAwait(false);
+                    await DisconnectInternalAsync(_packetReceiverTask, exception, null).ConfigureAwait(false);
                 }
             }
         }

Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs

@@ -136,6 +136,16 @@ namespace MQTTnet.Client.Options
             return this;
         }
 
+        public MqttClientOptionsBuilder WithTcpServer(Action<MqttClientTcpOptions> optionsBuilder)
+        {
+            if (optionsBuilder == null) throw new ArgumentNullException(nameof(optionsBuilder));
+
+            _tcpOptions = new MqttClientTcpOptions();
+            optionsBuilder.Invoke(_tcpOptions);
+
+            return this;
+        }
+
         public MqttClientOptionsBuilder WithProxy(string address, string username = null, string password = null, string domain = null, bool bypassOnLocal = false, string[] bypassList = null)
         {
             _proxyOptions = new MqttClientWebSocketProxyOptions
@@ -151,6 +161,15 @@ namespace MQTTnet.Client.Options
             return this;
         }
 
+        public MqttClientOptionsBuilder WithProxy(Action<MqttClientWebSocketProxyOptions> optionsBuilder)
+        {
+            if (optionsBuilder == null) throw new ArgumentNullException(nameof(optionsBuilder));
+
+            _proxyOptions = new MqttClientWebSocketProxyOptions();
+            optionsBuilder(_proxyOptions);
+            return this;
+        }
+
         public MqttClientOptionsBuilder WithWebSocketServer(string uri, MqttClientOptionsBuilderWebSocketParameters parameters = null)
         {
             _webSocketOptions = new MqttClientWebSocketOptions
@@ -163,9 +182,19 @@ namespace MQTTnet.Client.Options
             return this;
         }
 
+        public MqttClientOptionsBuilder WithWebSocketServer(Action<MqttClientWebSocketOptions> optionsBuilder)
+        {
+            if (optionsBuilder == null) throw new ArgumentNullException(nameof(optionsBuilder));
+
+            _webSocketOptions = new MqttClientWebSocketOptions();
+            optionsBuilder.Invoke(_webSocketOptions);
+
+            return this;
+        }
+
         public MqttClientOptionsBuilder WithTls(MqttClientOptionsBuilderTlsParameters parameters)
         {
-            _tlsParameters = parameters ?? throw new ArgumentNullException(nameof(parameters));
+            _tlsParameters = parameters;
             return this;
         }
 
@@ -174,6 +203,15 @@ namespace MQTTnet.Client.Options
             return WithTls(new MqttClientOptionsBuilderTlsParameters { UseTls = true });
         }
 
+        public MqttClientOptionsBuilder WithTls(Action<MqttClientOptionsBuilderTlsParameters> optionsBuilder)
+        {
+            if (optionsBuilder == null) throw new ArgumentNullException(nameof(optionsBuilder));
+
+            _tlsParameters = new MqttClientOptionsBuilderTlsParameters();
+            optionsBuilder(_tlsParameters);
+            return this;
+        }
+
         public IMqttClientOptions Build()
         {
             if (_tcpOptions == null && _webSocketOptions == null)

Source/MQTTnet/Formatter/V3/MqttV310DataConverter.cs

@@ -216,6 +216,7 @@ namespace MQTTnet.Formatter.V3
 
             return new MqttClientPublishResult
             {
+                PacketIdentifier = pubCompPacket.PacketIdentifier,
                 ReasonCode = MqttClientPublishReasonCode.Success
             };
         }

Source/MQTTnet/Formatter/V5/MqttV500DataConverter.cs

@@ -63,6 +63,13 @@ namespace MQTTnet.Formatter.V5
                 Payload = publishPacket.Payload,
                 QualityOfServiceLevel = publishPacket.QualityOfServiceLevel,
                 Retain = publishPacket.Retain,
+                ResponseTopic = publishPacket.Properties?.ResponseTopic,
+                ContentType = publishPacket.Properties?.ContentType,
+                CorrelationData = publishPacket.Properties?.CorrelationData,
+                MessageExpiryInterval = publishPacket.Properties?.MessageExpiryInterval,
+                SubscriptionIdentifier = publishPacket.Properties?.SubscriptionIdentifier,
+                TopicAlias = publishPacket.Properties?.TopicAlias,
+                PayloadFormatIndicator = publishPacket.Properties?.PayloadFormatIndicator,
                 UserProperties = publishPacket.Properties?.UserProperties ?? new List<MqttUserProperty>()
             };
         }
@@ -223,6 +230,7 @@ namespace MQTTnet.Formatter.V5
             {
                 return new MqttClientPublishResult
                 {
+                    PacketIdentifier = pubCompPacket.PacketIdentifier,
                     ReasonCode = MqttClientPublishReasonCode.UnspecifiedError,
                     ReasonString = pubCompPacket.Properties?.ReasonString,
                     UserProperties = pubCompPacket.Properties?.UserProperties
@@ -231,6 +239,7 @@ namespace MQTTnet.Formatter.V5
 
             var result = new MqttClientPublishResult
             {
+                PacketIdentifier = pubCompPacket.PacketIdentifier,
                 ReasonCode = MqttClientPublishReasonCode.Success,
                 ReasonString = pubCompPacket.Properties?.ReasonString,
                 UserProperties = pubCompPacket.Properties?.UserProperties

Source/MQTTnet/Formatter/V5/MqttV500PacketEncoder.cs

@@ -343,9 +343,6 @@ namespace MQTTnet.Formatter.V5
                 ThrowReasonCodeNotSetException();
             }
 
-            packetWriter.Write(packet.PacketIdentifier.Value);
-            packetWriter.Write((byte)packet.ReasonCode.Value);
-
             var propertiesWriter = new MqttV500PropertiesWriter();
             if (packet.Properties != null)
             {
@@ -353,7 +350,9 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            if (packetWriter.Length > 0 || packet.ReasonCode.Value != MqttPubRelReasonCode.Success)
+            packetWriter.Write(packet.PacketIdentifier.Value);
+            
+            if (propertiesWriter.Length > 0 || packet.ReasonCode.Value != MqttPubRelReasonCode.Success)
             {
                 packetWriter.Write((byte)packet.ReasonCode.Value);
                 propertiesWriter.WriteToPacket(packetWriter);
@@ -372,7 +371,6 @@ namespace MQTTnet.Formatter.V5
             }
 
             packetWriter.Write(packet.PacketIdentifier.Value);
-            packetWriter.Write((byte)packet.ReasonCode.Value);
             
             var propertiesWriter = new MqttV500PropertiesWriter();
             if (packet.Properties != null)
@@ -381,7 +379,7 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            if (packetWriter.Length > 0 || packet.ReasonCode.Value != MqttPubCompReasonCode.Success)
+            if (propertiesWriter.Length > 0 || packet.ReasonCode.Value != MqttPubCompReasonCode.Success)
             {
                 packetWriter.Write((byte)packet.ReasonCode.Value);
                 propertiesWriter.WriteToPacket(packetWriter);

Source/MQTTnet/Formatter/V5/MqttV500PropertiesWriter.cs

@@ -7,8 +7,11 @@ namespace MQTTnet.Formatter.V5
 {
     public class MqttV500PropertiesWriter
     {
+        // TODO: Consider lazy init on first write to avoid useless allocations.
         private readonly MqttPacketWriter _packetWriter = new MqttPacketWriter();
 
+        public int Length => _packetWriter.Length;
+
         public void WriteUserProperties(List<MqttUserProperty> userProperties)
         {
             if (userProperties == null || userProperties.Count == 0)

Source/MQTTnet/Server/MqttClientConnection.cs

@@ -138,7 +138,7 @@ namespace MQTTnet.Server
                     {
                         ReturnCode = MqttConnectReturnCode.ConnectionAccepted,
                         ReasonCode = MqttConnectReasonCode.Success,
-                        IsSessionPresent = Session.IsCleanSession
+                        IsSessionPresent = !Session.IsCleanSession
                     }).ConfigureAwait(false);
 
                 Session.IsCleanSession = false;

Source/MQTTnet/Server/MqttRetainedMessagesManager.cs

@@ -61,8 +61,9 @@ namespace MQTTnet.Server
                 using (await _messagesLock.WaitAsync().ConfigureAwait(false))
                 {
                     var saveIsRequired = false;
+                    var hasPayload = applicationMessage.Payload != null && applicationMessage.Payload.Length > 0;
 
-                    if (applicationMessage.Payload?.Any() != true)
+                    if (!hasPayload)
                     {
                         saveIsRequired = _messages.Remove(applicationMessage.Topic);
                         _logger.Verbose("Client '{0}' cleared retained message for topic '{1}'.", clientId, applicationMessage.Topic);

Tests/MQTTnet.Core.Tests/MqttClient_Tests.cs

@@ -11,7 +11,6 @@ using MQTTnet.Client.Disconnecting;
 using MQTTnet.Client.Options;
 using MQTTnet.Client.Subscribing;
 using MQTTnet.Exceptions;
-using MQTTnet.Formatter;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
 using MQTTnet.Tests.Mockups;
@@ -21,6 +20,34 @@ namespace MQTTnet.Tests
     [TestClass]
     public class Client_Tests
     {
+        [TestMethod]
+        public async Task PacketIdentifier_In_Publish_Result()
+        {
+            using (var testEnvironment = new TestEnvironment())
+            {
+                await testEnvironment.StartServerAsync();
+                var client = await testEnvironment.ConnectClientAsync();
+
+                var result = await client.PublishAsync("a", "a", MqttQualityOfServiceLevel.AtMostOnce);
+                Assert.AreEqual(null, result.PacketIdentifier);
+
+                result = await client.PublishAsync("b", "b", MqttQualityOfServiceLevel.AtMostOnce);
+                Assert.AreEqual(null, result.PacketIdentifier);
+
+                result = await client.PublishAsync("a", "a", MqttQualityOfServiceLevel.AtLeastOnce);
+                Assert.AreEqual((ushort)1, result.PacketIdentifier);
+
+                result = await client.PublishAsync("b", "b", MqttQualityOfServiceLevel.AtLeastOnce);
+                Assert.AreEqual((ushort)2, result.PacketIdentifier);
+
+                result = await client.PublishAsync("a", "a", MqttQualityOfServiceLevel.ExactlyOnce);
+                Assert.AreEqual((ushort)3, result.PacketIdentifier);
+
+                result = await client.PublishAsync("b", "b", MqttQualityOfServiceLevel.ExactlyOnce);
+                Assert.AreEqual((ushort)4, result.PacketIdentifier);
+            }
+        }
+        
         [TestMethod]
         public async Task Invalid_Connect_Throws_Exception()
         {

Tests/MQTTnet.Core.Tests/MqttTcpChannel_Tests.cs

@@ -15,11 +15,11 @@ namespace MQTTnet.Tests
         public async Task Dispose_Channel_While_Used()
         {
             var ct = new CancellationTokenSource();
+            var serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
 
             try
             {
-                var serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                serverSocket.Bind(new IPEndPoint(IPAddress.Any, 50001));
-                serverSocket.Bind(new IPEndPoint(IPAddress.Any, 50000));
                 serverSocket.Listen(0);
 
 #pragma warning disable 4014
@@ -35,7 +35,7 @@ namespace MQTTnet.Tests
                 }, ct.Token);
 
                 var clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
-                await clientSocket.ConnectAsync(IPAddress.Loopback, 50000);
+                await clientSocket.ConnectAsync(IPAddress.Loopback, 50001);
 
                 await Task.Delay(100, ct.Token);
 
@@ -68,6 +68,7 @@ namespace MQTTnet.Tests
             finally
             {
                 ct.Cancel(false);
+                serverSocket.Dispose();
             }
         }
     }

Tests/MQTTnet.Core.Tests/Server_Tests.cs

@@ -54,6 +54,20 @@ namespace MQTTnet.Tests
                 1);
         }
 
+        [TestMethod]
+        public async Task Use_Clean_Session()
+        {
+            using (var testEnvironment = new TestEnvironment())
+            {
+                await testEnvironment.StartServerAsync();
+
+                var client = testEnvironment.CreateClient();
+                var connectResult = await client.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("localhost", testEnvironment.ServerPort).WithCleanSession().Build());
+
+                Assert.IsFalse(connectResult.IsSessionPresent);
+            }
+        }
+
         [TestMethod]
         public async Task Will_Message_Do_Not_Send()
         {
@@ -61,7 +75,7 @@ namespace MQTTnet.Tests
             {
                 var receivedMessagesCount = 0;
 
-                await testEnvironment.StartServerAsync(new MqttServerOptionsBuilder());
+                await testEnvironment.StartServerAsync();
 
                 var willMessage = new MqttApplicationMessageBuilder().WithTopic("My/last/will").WithAtMostOnceQoS().Build();
 
@@ -540,7 +554,7 @@ namespace MQTTnet.Tests
         }
 
         [TestMethod]
-        public async Task Clear_Retained_Message()
+        public async Task Clear_Retained_Message_With_Empty_Payload()
         {
             using (var testEnvironment = new TestEnvironment())
             {
@@ -567,6 +581,34 @@ namespace MQTTnet.Tests
             }
         }
 
+        [TestMethod]
+        public async Task Clear_Retained_Message_With_Null_Payload()
+        {
+            using (var testEnvironment = new TestEnvironment())
+            {
+                var receivedMessagesCount = 0;
+
+                await testEnvironment.StartServerAsync();
+
+                var c1 = await testEnvironment.ConnectClientAsync();
+
+                await c1.PublishAsync(new MqttApplicationMessageBuilder().WithTopic("retained").WithPayload(new byte[3]).WithRetainFlag().Build());
+                await c1.PublishAsync(new MqttApplicationMessageBuilder().WithTopic("retained").WithPayload((byte[])null).WithRetainFlag().Build());
+
+                await c1.DisconnectAsync();
+
+                var c2 = await testEnvironment.ConnectClientAsync();
+
+                c2.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
+
+                await Task.Delay(200);
+                await c2.SubscribeAsync(new TopicFilter { Topic = "retained", QualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce });
+                await Task.Delay(500);
+
+                Assert.AreEqual(0, receivedMessagesCount);
+            }
+        }
+
         [TestMethod]
         public async Task Intercept_Application_Message()
         {

Tests/MQTTnet.TestApp.NetCore/Program.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Net.Security;
+using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Client;
@@ -118,4 +120,22 @@ namespace MQTTnet.TestApp.NetCore
             return Task.FromResult(retainedMessages);
         }
     }
+
+    public class WikiCode
+    {
+        public void Code()
+        {
+            //Validate certificate.
+            var options = new MqttClientOptionsBuilder()
+                .WithTls(new MqttClientOptionsBuilderTlsParameters
+                {
+                    CertificateValidationCallback = (X509Certificate x, X509Chain y, SslPolicyErrors z, IMqttClientOptions o) =>
+                        {
+                            // TODO: Check conditions of certificate by using above parameters.
+                            return true;
+                        }
+                })
+                .Build();
+        }
+    }
 }

Tests/MQTTnet.TestApp.UniversalWindows/MainPage.xaml.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.ObjectModel;
+using System.Net.Security;
+using System.Security.Cryptography.X509Certificates;
 using System.Text;
 using System.Threading.Tasks;
 using Windows.Security.Cryptography.Certificates;
@@ -714,6 +716,25 @@ namespace MQTTnet.TestApp.UniversalWindows
                 var mqttServer = new MqttFactory().CreateMqttServer();
             }
 
+            {
+                // Setup subscription interceptor.
+                var options = new MqttServerOptionsBuilder()
+                    .WithSubscriptionInterceptor(context =>
+                    {
+                        if (context.TopicFilter.Topic.StartsWith("admin/foo/bar") && context.ClientId != "theAdmin")
+                        {
+                            context.AcceptSubscription = false;
+                        }
+
+                        if (context.TopicFilter.Topic.StartsWith("the/secret/stuff") && context.ClientId != "Imperator")
+                        {
+                            context.AcceptSubscription = false;
+                            context.CloseConnection = true;
+                        }
+                    })
+                    .Build();
+            }
+
             {
                 // Setup and start a managed MQTT client.
                 var options = new ManagedMqttClientOptionsBuilder()

appveyor.yml

@@ -14,5 +14,5 @@ build:
   verbosity: minimal
 
 test_script:
-- cmd: dotnet vstest "%APPVEYOR_BUILD_FOLDER%\Tests\MQTTnet.Core.Tests\bin\Release\netcoreapp2.1\MQTTnet.Core.Tests.dll"
+- cmd: dotnet vstest "%APPVEYOR_BUILD_FOLDER%\Tests\MQTTnet.Core.Tests\bin\Release\netcoreapp2.1\MQTTnet.Tests.dll"
 - cmd: dotnet vstest "%APPVEYOR_BUILD_FOLDER%\Tests\MQTTnet.AspNetCore.Tests\bin\Release\netcoreapp2.1\MQTTnet.AspNetCore.Tests.dll"