Backport of: 2129 cancellation token backport (#2144)

* Increase version

* Update release notes

* Adjust cancellation token handling

* Fix CI build

.github/workflows/ReleaseNotes.md

@@ -1,5 +1 @@
-* Core: Fixed issue when parsing AUTH packet with 0 length body (#2039).
-* nuget: Changed code signing and nuget certificate (**BREAKING CHANGE**).
-* TopicTemplates: Updated samples, parameter validation (#2022).
-* ManagedClient: Switch SubscribeAsync/UnsubscribeAsync to IEnumerable<string> (#2026).
-* Server: Fix _LoadingRetainedMessageAsync_ not executed (#2025).
+* Client: Fixed wrong timeout for keep alive check (thanks to @Erw1nT, #2129)

.github/workflows/ci.yml

@@ -3,7 +3,7 @@ name: CI
 on: [push, pull_request]
 
 env:
-  VERSION: "4.3.7.${{github.run_number}}"
+  VERSION: "4.3.8.${{github.run_number}}"
 
 jobs:
   build:
@@ -12,7 +12,7 @@ jobs:
 
     steps:
       - name: Setup Windows SDK
-        uses: GuillaumeFalourd/setup-windows10-sdk-action@v1
+        uses: GuillaumeFalourd/setup-windows10-sdk-action@v2.4
         with:
           sdk-version: 18362
 

Source/MQTTnet/Client/MqttClient.cs

@@ -1051,10 +1051,13 @@ async Task TrySendKeepAliveMessages(CancellationToken cancellationToken)
 
                     if (timeWithoutPacketSent > keepAlivePeriod)
                     {
-                        using (var timeoutCancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken))
+                        using (var pingTimeout = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken))
                         {
-                            timeoutCancellationTokenSource.CancelAfter(Options.Timeout);
-                            await PingAsync(timeoutCancellationTokenSource.Token).ConfigureAwait(false);
+                            // We already reached the keep alive timeout. Due to the RFC part [MQTT-3.1.2-24] the server will wait another
+                            // 1/2 of the keep alive time. So we can also use this value as the timeout.
+                            pingTimeout.CancelAfter((int)(keepAlivePeriod.TotalMilliseconds / 2));
+
+                            await PingAsync(pingTimeout.Token).ConfigureAwait(false);
                         }
                     }