Merge branch 'develop'

Build/MQTTnet.nuspec

@@ -11,8 +11,7 @@
     <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) and supports v3.1.0, v3.1.1 and v5.0.0 of the MQTT protocol.</description>
     <releaseNotes>
-* [Core] Fixed wrong versions in nuget packages.
+* [Server] Moved new socket options to TCP options to avoid incompatibility with Linux hosts.
-* [Server] The TCP address is now reused when starting which should prevent "port in used" error when restarting.
     </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> 

Source/MQTTnet/Implementations/MqttTcpServerListener.cs

@@ -60,8 +60,17 @@ namespace MQTTnet.Implementations
                 _logger.Info($"Starting TCP listener for {_localEndPoint} TLS={_tlsCertificate != null}.");
 
                 _socket = new Socket(_addressFamily, SocketType.Stream, ProtocolType.Tcp);
-                _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
+
-                _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.NoDelay, true);
+                if (_options.ReuseAddress)
+                {
+                    _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
+                }
+                
+                if (_options.NoDelay)
+                {
+                    _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.NoDelay, true);
+                }
+                
                 _socket.Bind(_localEndPoint);
                 _socket.Listen(_options.ConnectionBacklog);
 

Source/MQTTnet/Server/MqttServerTcpEndpointBaseOptions.cs

@@ -19,5 +19,10 @@ namespace MQTTnet.Server
         public IPAddress BoundInterNetworkAddress { get; set; } = IPAddress.Any;
 
         public IPAddress BoundInterNetworkV6Address { get; set; } = IPAddress.IPv6Any;
+
+        /// <summary>
+        /// This requires admin permissions on Linux.
+        /// </summary>
+        public bool ReuseAddress { get; set; }
     }
 }