Fix exception handling issues (#1082).

Source/MQTTnet/Adapter/MqttConnectingFailedException.cs

@@ -1,17 +1,19 @@
-using MQTTnet.Client.Connecting;
+using System;
+using MQTTnet.Client.Connecting;
 using MQTTnet.Exceptions;
 
 namespace MQTTnet.Adapter
 {
-    public class MqttConnectingFailedException : MqttCommunicationException
+    public sealed class MqttConnectingFailedException : MqttCommunicationException
     {
-        public MqttConnectingFailedException(MqttClientAuthenticateResult result)
-            : base($"Connecting with MQTT server failed ({result.ResultCode.ToString()}).")
+        public MqttConnectingFailedException(string message, Exception innerException, MqttClientAuthenticateResult authenticateResult)
+            : base(message, innerException)
         {
-            Result = result;
+            Result = authenticateResult;
         }
 
         public MqttClientAuthenticateResult Result { get; }
-        public MqttClientConnectResultCode ResultCode => Result.ResultCode;
+
+        public MqttClientConnectResultCode ResultCode => Result?.ResultCode ?? MqttClientConnectResultCode.UnspecifiedError;
     }
 }

Source/MQTTnet/Client/MqttClient.cs

@@ -280,16 +280,25 @@ namespace MQTTnet.Client
 
         async Task<MqttClientAuthenticateResult> AuthenticateAsync(IMqttChannelAdapter channelAdapter, MqttApplicationMessage willApplicationMessage, CancellationToken cancellationToken)
         {
-            var connectPacket = channelAdapter.PacketFormatterAdapter.DataConverter.CreateConnectPacket(
-                willApplicationMessage,
-                Options);
+            MqttClientAuthenticateResult result;
 
-            var connAckPacket = await SendAndReceiveAsync<MqttConnAckPacket>(connectPacket, cancellationToken).ConfigureAwait(false);
-            var result = channelAdapter.PacketFormatterAdapter.DataConverter.CreateClientConnectResult(connAckPacket);
+            try
+            {
+                var connectPacket = channelAdapter.PacketFormatterAdapter.DataConverter.CreateConnectPacket(
+                    willApplicationMessage,
+                    Options);
+
+                var connAckPacket = await SendAndReceiveAsync<MqttConnAckPacket>(connectPacket, cancellationToken).ConfigureAwait(false);
+                result = channelAdapter.PacketFormatterAdapter.DataConverter.CreateClientConnectResult(connAckPacket);
+            }
+            catch (Exception exception)
+            {
+                throw new MqttConnectingFailedException($"Error while authenticating. {exception.Message}", exception, null);
+            }
 
             if (result.ResultCode != MqttClientConnectResultCode.Success)
             {
-                throw new MqttConnectingFailedException(result);
+                throw new MqttConnectingFailedException($"Connecting with MQTT server failed ({result.ResultCode}).", null, result);
             }
 
             _logger.Verbose("Authenticated MQTT connection with server established.");
@@ -404,10 +413,10 @@ namespace MQTTnet.Client
                     _sendTracker.Restart();
                     await _adapter.SendPacketAsync(requestPacket, cancellationToken).ConfigureAwait(false);
                 }
-                catch (Exception e)
+                catch (Exception exception)
                 {
-                    _logger.Warning(e, "Error when sending request packet ({0}).", requestPacket.GetType().Name);
-                    packetAwaiter.Cancel();
+                    _logger.Warning(exception, "Error when sending request packet ({0}).", requestPacket.GetType().Name);
+                    packetAwaiter.Fail(exception);
                 }
 
                 try

Tests/MQTTnet.Core.Tests/Server_Tests.cs

@@ -1,4 +1,4 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Adapter;
 using MQTTnet.Client;
 using MQTTnet.Client.Connecting;
@@ -69,9 +69,9 @@ namespace MQTTnet.Tests
                     .WithCredentials(username, password)
                     .Build();
 
-                var ex = await Assert.ThrowsExceptionAsync<MqttCommunicationException>(async () => await client.ConnectAsync(clientOptions));
+                var ex = await Assert.ThrowsExceptionAsync<MqttConnectingFailedException>(async () => await client.ConnectAsync(clientOptions));
                 Assert.IsInstanceOfType(ex.InnerException, typeof(MqttProtocolViolationException));
-                Assert.AreEqual("If the User Name Flag is set to 0, the Password Flag MUST be set to 0 [MQTT-3.1.2-22].", ex.Message, false);
+                Assert.AreEqual("Error while authenticating. If the User Name Flag is set to 0, the Password Flag MUST be set to 0 [MQTT-3.1.2-22].", ex.Message, false);
             }
         }
 
@@ -466,7 +466,7 @@ namespace MQTTnet.Tests
         public async Task Publish_Multiple_Clients()
         {
             var receivedMessagesCount = 0;
-            
+
             using (var testEnvironment = new TestEnvironment(TestContext))
             {
                 await testEnvironment.StartServerAsync();
@@ -496,7 +496,7 @@ namespace MQTTnet.Tests
                 }
 
                 SpinWait.SpinUntil(() => receivedMessagesCount == 1000, TimeSpan.FromSeconds(20));
-                
+
                 Assert.AreEqual(1000, receivedMessagesCount);
             }
         }