From 36736914bcebcfe6851319e71a932a170bbff806 Mon Sep 17 00:00:00 2001
From: Christian <6939810+chkr1011@users.noreply.github.com>
Date: Sun, 23 Oct 2022 07:51:19 +0200
Subject: [PATCH] Fix Xamarin connect freeze (#1545)

---
 .github/workflows/ReleaseNotes.md             |  1 +
 .../MQTTnet.Tests/Client/MqttClient_Tests.cs  |  2 +-
 Source/MQTTnet/Adapter/MqttChannelAdapter.cs  | 23 +++++++++++++++++--
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/ReleaseNotes.md b/.github/workflows/ReleaseNotes.md
index e69de29b..caaab403 100644
--- a/.github/workflows/ReleaseNotes.md
+++ b/.github/workflows/ReleaseNotes.md
@@ -0,0 +1 @@
+* [Client] Fixed connection freeze when using Xamarin etc.
\ No newline at end of file
diff --git a/Source/MQTTnet.Tests/Client/MqttClient_Tests.cs b/Source/MQTTnet.Tests/Client/MqttClient_Tests.cs
index 43a72ab4..b073c5fe 100644
--- a/Source/MQTTnet.Tests/Client/MqttClient_Tests.cs
+++ b/Source/MQTTnet.Tests/Client/MqttClient_Tests.cs
@@ -123,7 +123,7 @@ namespace MQTTnet.Tests.Client
                     //Assert.IsInstanceOfType(exception.InnerException, typeof(SocketException));
                 }
 
-                await Task.Delay(100); // disconnected handler is called async
+                await LongTestDelay(); // disconnected handler is called async
                 Assert.IsTrue(disconnectHandlerCalled);
             }
         }
diff --git a/Source/MQTTnet/Adapter/MqttChannelAdapter.cs b/Source/MQTTnet/Adapter/MqttChannelAdapter.cs
index 5a0bcd6c..5af179f2 100644
--- a/Source/MQTTnet/Adapter/MqttChannelAdapter.cs
+++ b/Source/MQTTnet/Adapter/MqttChannelAdapter.cs
@@ -23,7 +23,7 @@ namespace MQTTnet.Adapter
     {
         const uint ErrorOperationAborted = 0x800703E3;
         const int ReadBufferSize = 4096;
-        
+
         readonly IMqttChannel _channel;
         readonly byte[] _fixedHeaderBuffer = new byte[2];
         readonly MqttNetSourceLogger _logger;
@@ -73,7 +73,26 @@ namespace MQTTnet.Adapter
 
             try
             {
-                await _channel.ConnectAsync(cancellationToken).ConfigureAwait(false);
+                /*
+                 * We have to implement a small workaround here to support connecting in Xamarin
+                 * with a disabled WiFi network. If the WiFi is disabled the connect method will
+                 * block forever. Even a cancellation token is not supported properly.
+                 */
+
+                var connectTask = _channel.ConnectAsync(cancellationToken);
+
+                var timeout = new TaskCompletionSource<object>();
+                using (cancellationToken.Register(() => timeout.TrySetResult(null)))
+                {
+                    await Task.WhenAny(connectTask, timeout.Task).ConfigureAwait(false);
+                    if (timeout.Task.IsCompleted && !connectTask.IsCompleted)
+                    {
+                        throw new OperationCanceledException("MQTT connect cancelled.", cancellationToken);
+                    }
+
+                    // Make sure that the exception from the connect task gets thrown.
+                    await connectTask.ConfigureAwait(false);
+                }
             }
             catch (Exception exception)
             {