Merge branch 'master' of https://github.com/chkr1011/MQTTnet into feature/Reason_Code_In_Subscription_Interceptor

# Conflicts:
#	Source/MQTTnet/Server/Internal/MqttClientConnectionStatistics.cs

Source/MQTTnet/Server/Internal/MqttClientConnectionStatistics.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Threading;
 using MQTTnet.Packets;
 
@@ -24,11 +24,17 @@ namespace MQTTnet.Server
 
             LastNonKeepAlivePacketReceivedTimestamp = ConnectedTimestamp;
         }
-
+        
         public DateTime ConnectedTimestamp { get; }
 
+        /// <summary>
+        /// Timestamp of the last package that has been sent to the client ("received" from the client's perspective)
+        /// </summary>
         public DateTime LastPacketReceivedTimestamp { get; private set; }
-
+                
+        /// <summary>
+        /// Timestamp of the last package that has been received from the client ("sent" from the client's perspective)
+        /// </summary>
         public DateTime LastPacketSentTimestamp { get; private set; }
         
         public DateTime LastNonKeepAlivePacketReceivedTimestamp { get; private set; }

Source/MQTTnet/Server/Internal/MqttServerKeepAliveMonitor.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Client;
@@ -94,7 +94,7 @@ namespace MQTTnet.Server
                 // If the client sends 1 sec. the server will allow up to 1.5 seconds.
                 var maxDurationWithoutPacket = connection.KeepAlivePeriod * 1.5D;
 
-                var secondsWithoutPackage = (now - connection.Statistics.LastPacketReceivedTimestamp).TotalSeconds;
+                var secondsWithoutPackage = (now - connection.Statistics.LastPacketSentTimestamp).TotalSeconds;
                 if (secondsWithoutPackage < maxDurationWithoutPacket)
                 {
                     // A packet was received before the timeout is affected.

Tests/MQTTnet.Core.Tests/Client/MqttClient_Tests.cs

@@ -649,6 +649,39 @@ namespace MQTTnet.Tests.Client
             }
         }
 
+        [TestMethod]
+        public async Task Publish_QoS_0_Over_Period_Exceeding_KeepAlive()
+        {
+            using (var testEnvironment = new TestEnvironment(TestContext))
+            {
+                const int KeepAlivePeriodSecs = 3;
+
+                await testEnvironment.StartServer();
+
+                var options = new MqttClientOptionsBuilder().WithKeepAlivePeriod(TimeSpan.FromSeconds(KeepAlivePeriodSecs));
+                var client = await testEnvironment.ConnectClient(options);
+                var message = new MqttApplicationMessageBuilder().WithTopic("a").Build();
+
+                try
+                {
+                    // Publish messages over a time period exceeding the keep alive period.
+                    // This should not cause an exception because of, i.e. "Client disconnected".
+
+                    for (var count = 0; count < KeepAlivePeriodSecs * 3; ++count)
+                    {
+                        // Send Publish requests well before the keep alive period expires
+                        await client.PublishAsync(message);
+                        await Task.Delay(1000);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Assert.Fail(ex.Message);
+                }
+            }
+        }
+
+
         [TestMethod]
         public async Task Subscribe_In_Callback_Events()
         {