Add event which is fired before a publish packet is released

MQTTnet.sln.DotSettings

@@ -243,5 +243,6 @@ See the LICENSE file in the project root for more information.</s:String>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=PINGREQ/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=PINGRESP/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=PUBCOMP/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=PUBREC/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Tnet/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=unsub/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

Samples/Diagnostics/PackageInspection_Samples.cs

@@ -26,7 +26,7 @@ public static class PackageInspection_Samples
                 .WithTcpServer("broker.hivemq.com")
                 .Build();
             
-            mqttClient.InspectPackage += OnInspectPackage;
+            mqttClient.InspectPackageAsync += OnInspectPackage;
             
             await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
             

Source/MQTTnet.Tests/Diagnostics/PacketInspection_Tests.cs

@@ -30,7 +30,7 @@ namespace MQTTnet.Tests.Diagnostics
 
                     var packets = new List<string>();
                     
-                    mqttClient.InspectPackage += eventArgs =>
+                    mqttClient.InspectPackageAsync += eventArgs =>
                     {
                         packets.Add(eventArgs.Direction + ":" + Convert.ToBase64String(eventArgs.Buffer));
                         return CompletedTask.Instance;

Source/MQTTnet.Tests/Server/General.cs

@@ -954,7 +954,7 @@ namespace MQTTnet.Tests.Server
 
                 var client = testEnvironment.CreateClient();
 
-                client.InspectPackage += e =>
+                client.InspectPackageAsync += e =>
                 {
                     if (e.Buffer.Length > 0)
                     {

Source/MQTTnet/Client/IMqttClient.cs

@@ -9,13 +9,15 @@ namespace MQTTnet.Client
     {
         event Func<MqttApplicationMessageReceivedEventArgs, Task> ApplicationMessageReceivedAsync;
 
+        event Func<MqttClientBeforeReleasePublishPacketEventArgs, Task> BeforeReleasePublishPacketAsync;
+
         event Func<MqttClientConnectedEventArgs, Task> ConnectedAsync;
 
         event Func<MqttClientConnectingEventArgs, Task> ConnectingAsync;
 
         event Func<MqttClientDisconnectedEventArgs, Task> DisconnectedAsync;
 
-        event Func<InspectMqttPacketEventArgs, Task> InspectPackage;
+        event Func<InspectMqttPacketEventArgs, Task> InspectPackageAsync;
 
         bool IsConnected { get; }
 

Source/MQTTnet/Client/MqttClient.cs

@@ -21,6 +21,7 @@ namespace MQTTnet.Client
         readonly IMqttClientAdapterFactory _adapterFactory;
         readonly MqttApplicationMessageFactory _applicationMessageFactory = new MqttApplicationMessageFactory();
         readonly AsyncEvent<MqttApplicationMessageReceivedEventArgs> _applicationMessageReceivedEvent = new AsyncEvent<MqttApplicationMessageReceivedEventArgs>();
+        readonly AsyncEvent<MqttClientBeforeReleasePublishPacketEventArgs> _beforeReleasePublishPacketEvent = new AsyncEvent<MqttClientBeforeReleasePublishPacketEventArgs>();
 
         readonly MqttClientPublishResultFactory _clientPublishResultFactory = new MqttClientPublishResultFactory();
         readonly MqttClientSubscribeResultFactory _clientSubscribeResultFactory = new MqttClientSubscribeResultFactory();
@@ -63,6 +64,12 @@ namespace MQTTnet.Client
             remove => _applicationMessageReceivedEvent.RemoveHandler(value);
         }
 
+        public event Func<MqttClientBeforeReleasePublishPacketEventArgs, Task> BeforeReleasePublishPacketAsync
+        {
+            add => _beforeReleasePublishPacketEvent.AddHandler(value);
+            remove => _beforeReleasePublishPacketEvent.RemoveHandler(value);
+        }
+
         public event Func<MqttClientConnectedEventArgs, Task> ConnectedAsync
         {
             add => _connectedEvent.AddHandler(value);
@@ -81,7 +88,7 @@ namespace MQTTnet.Client
             remove => _disconnectedEvent.RemoveHandler(value);
         }
 
-        public event Func<InspectMqttPacketEventArgs, Task> InspectPackage
+        public event Func<InspectMqttPacketEventArgs, Task> InspectPackageAsync
         {
             add => _inspectPacketEvent.AddHandler(value);
             remove => _inspectPacketEvent.RemoveHandler(value);
@@ -259,7 +266,9 @@ namespace MQTTnet.Client
             }
         }
 
-        public async Task<MqttClientReleasePublishPacketResult> ReleasePublishPacketAsync(MqttClientReleasePublishPacketOptions options, CancellationToken cancellationToken = default)
+        public async Task<MqttClientReleasePublishPacketResult> ReleasePublishPacketAsync(
+            MqttClientReleasePublishPacketOptions options,
+            CancellationToken cancellationToken = default)
         {
             if (options == null)
             {
@@ -281,8 +290,23 @@ namespace MQTTnet.Client
                 throw new InvalidOperationException("Manually releasing PUBLISH packets requires the feature _AutoReleasePublishPackets_ disabled in the client options.");
             }
 
+            var eventArgs = new MqttClientBeforeReleasePublishPacketEventArgs(options.PacketIdentifier);
+            await _beforeReleasePublishPacketEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
+            
             var pubRelPacket = _packetFactories.PubRel.Create(options);
-            var pubCompPacket = await SendAndReceiveAsync<MqttPubCompPacket>(pubRelPacket, cancellationToken).ConfigureAwait(false);
+                
+            MqttPubCompPacket pubCompPacket;
+            if (cancellationToken.CanBeCanceled)
+            {
+                pubCompPacket = await SendAndReceiveAsync<MqttPubCompPacket>(pubRelPacket, cancellationToken).ConfigureAwait(false);
+            }
+            else
+            {
+                using (var timeout = new CancellationTokenSource(Options.Timeout))
+                {
+                    pubCompPacket = await SendAndReceiveAsync<MqttPubCompPacket>(pubRelPacket, timeout.Token).ConfigureAwait(false);
+                }
+            }
 
             return new MqttClientReleasePublishPacketResult(pubCompPacket.PacketIdentifier, pubCompPacket.ReasonString, pubCompPacket.UserProperties);
         }
@@ -628,7 +652,7 @@ namespace MQTTnet.Client
             {
                 // The packet is unknown. Probably due to a restart of the client.
                 // So wen send this to the server to trigger a full resend of the message.
-                var pubRelPacket = _packetFactories.PubRel.Create(pubRecPacket, MqttApplicationMessageReceivedReasonCode.PacketIdentifierNotFound);
+                var pubRelPacket = _packetFactories.PubRel.Create(pubRecPacket, MqttPubRelReasonCode.PacketIdentifierNotFound);
                 return SendAsync(pubRelPacket, cancellationToken);
             }
 
@@ -669,7 +693,10 @@ namespace MQTTnet.Client
                 return _clientPublishResultFactory.Create(pubRecPacket);
             }
 
-            var pubRelPacket = _packetFactories.PubRel.Create(pubRecPacket, MqttApplicationMessageReceivedReasonCode.Success);
+            var eventArgs = new MqttClientBeforeReleasePublishPacketEventArgs(pubRecPacket.PacketIdentifier);
+            await _beforeReleasePublishPacketEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
+            
+            var pubRelPacket = _packetFactories.PubRel.Create(pubRecPacket, MqttPubRelReasonCode.Success);
             var pubCompPacket = await SendAndReceiveAsync<MqttPubCompPacket>(pubRelPacket, cancellationToken).ConfigureAwait(false);
             return _clientPublishResultFactory.Create(pubRecPacket, pubCompPacket);
         }

Source/MQTTnet/Client/Publishing/MqttClientBeforeReleasePublishPacketEventArgs.cs

@@ -0,0 +1,18 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+
+namespace MQTTnet.Client
+{
+    public sealed class MqttClientBeforeReleasePublishPacketEventArgs : EventArgs
+    {
+        public MqttClientBeforeReleasePublishPacketEventArgs(ushort packetIdentifier)
+        {
+            PacketIdentifier = packetIdentifier;
+        }
+
+        public ushort PacketIdentifier { get; }
+    }
+}

Source/MQTTnet/Client/Publishing/MqttClientPublishResult.cs

@@ -9,6 +9,14 @@ namespace MQTTnet.Client
 {
     public sealed class MqttClientPublishResult
     {
+        public MqttClientPublishResult(ushort? packetIdentifier, MqttClientPublishReasonCode reasonCode, string reasonString, IReadOnlyCollection<MqttUserProperty> userProperties)
+        {
+            PacketIdentifier = packetIdentifier;
+            ReasonCode = reasonCode;
+            ReasonString = reasonString;
+            UserProperties = userProperties;
+        }
+
         /// <summary>
         ///     Returns if the overall status of the publish is a success. This can be the reason code _Success_ or
         ///     _NoMatchingSubscribers_. _NoMatchingSubscribers_ usually indicates only that no other client is interested in the topic but overall transmit
@@ -19,19 +27,19 @@ namespace MQTTnet.Client
         /// <summary>
         ///     Gets the packet identifier which was used for this publish.
         /// </summary>
-        public ushort? PacketIdentifier { get; set; }
+        public ushort? PacketIdentifier { get; }
 
         /// <summary>
         ///     Gets or sets the reason code.
         ///     Hint: MQTT 5 feature only.
         /// </summary>
-        public MqttClientPublishReasonCode ReasonCode { get; set; } = MqttClientPublishReasonCode.Success;
+        public MqttClientPublishReasonCode ReasonCode { get; }
 
         /// <summary>
         ///     Gets or sets the reason string.
         ///     Hint: MQTT 5 feature only.
         /// </summary>
-        public string ReasonString { get; set; }
+        public string ReasonString { get; }
 
         /// <summary>
         ///     Gets or sets the user properties.
@@ -42,6 +50,6 @@ namespace MQTTnet.Client
         ///     The feature is very similar to the HTTP header concept.
         ///     Hint: MQTT 5 feature only.
         /// </summary>
-        public IReadOnlyCollection<MqttUserProperty> UserProperties { get; internal set; }
+        public IReadOnlyCollection<MqttUserProperty> UserProperties { get; }
     }
 }

Source/MQTTnet/Client/Publishing/MqttClientPublishResultFactory.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Collections.Generic;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
@@ -10,8 +11,8 @@ namespace MQTTnet.Client
 {
     public sealed class MqttClientPublishResultFactory
     {
-        static readonly MqttClientPublishResult EmptySuccessResult = new MqttClientPublishResult();
         static readonly IReadOnlyCollection<MqttUserProperty> EmptyUserProperties = new List<MqttUserProperty>();
+        static readonly MqttClientPublishResult EmptySuccessResult = new MqttClientPublishResult(null, MqttClientPublishReasonCode.Success, null, EmptyUserProperties);
 
         public MqttClientPublishResult Create(MqttPubAckPacket pubAckPacket)
         {
@@ -21,70 +22,55 @@ namespace MQTTnet.Client
                 return EmptySuccessResult;
             }
 
-            var result = new MqttClientPublishResult
-            {
-                // Both enums have the same values. So it can be easily converted.
-                ReasonCode = (MqttClientPublishReasonCode)(int)pubAckPacket.ReasonCode,
-                PacketIdentifier = pubAckPacket.PacketIdentifier,
-                ReasonString = pubAckPacket.ReasonString,
-                UserProperties = pubAckPacket.UserProperties ?? EmptyUserProperties
-            };
+            var result = new MqttClientPublishResult(
+                pubAckPacket.PacketIdentifier,
+                (MqttClientPublishReasonCode)(int)pubAckPacket.ReasonCode,
+                pubAckPacket.ReasonString,
+                pubAckPacket.UserProperties ?? EmptyUserProperties);
 
             return result;
         }
 
         public MqttClientPublishResult Create(MqttPubRecPacket pubRecPacket)
         {
-            return new MqttClientPublishResult
+            if (pubRecPacket == null)
             {
-                PacketIdentifier = pubRecPacket.PacketIdentifier,
-                ReasonCode = (MqttClientPublishReasonCode)(int)pubRecPacket.ReasonCode,
-                ReasonString = pubRecPacket.ReasonString,
-                UserProperties = pubRecPacket.UserProperties
-            };
+                throw new ArgumentNullException(nameof(pubRecPacket));
+            }
+
+            return new MqttClientPublishResult(
+                pubRecPacket.PacketIdentifier,
+                (MqttClientPublishReasonCode)(int)pubRecPacket.ReasonCode,
+                pubRecPacket.ReasonString,
+                pubRecPacket.UserProperties ?? EmptyUserProperties);
         }
-        
+
         public MqttClientPublishResult Create(MqttPubRecPacket pubRecPacket, MqttPubCompPacket pubCompPacket)
         {
             if (pubRecPacket == null || pubCompPacket == null)
             {
-                return new MqttClientPublishResult
-                {
-                    ReasonCode = MqttClientPublishReasonCode.UnspecifiedError
-                };
+                return new MqttClientPublishResult(null, MqttClientPublishReasonCode.UnspecifiedError, null, EmptyUserProperties);
             }
 
-            MqttClientPublishResult result;
-
             // The PUBCOMP is the last packet in QoS 2. So we use the results from that instead of PUBREC.
             if (pubCompPacket.ReasonCode == MqttPubCompReasonCode.PacketIdentifierNotFound)
             {
-                result = new MqttClientPublishResult
-                {
-                    PacketIdentifier = pubCompPacket.PacketIdentifier,
-                    ReasonCode = MqttClientPublishReasonCode.UnspecifiedError,
-                    ReasonString = pubCompPacket.ReasonString,
-                    UserProperties = pubCompPacket.UserProperties ?? EmptyUserProperties
-                };
-
-                return result;
+                return new MqttClientPublishResult(
+                    pubCompPacket.PacketIdentifier,
+                    MqttClientPublishReasonCode.UnspecifiedError,
+                    pubCompPacket.ReasonString,
+                    pubCompPacket.UserProperties ?? EmptyUserProperties);
             }
 
-            result = new MqttClientPublishResult
-            {
-                PacketIdentifier = pubCompPacket.PacketIdentifier,
-                ReasonCode = MqttClientPublishReasonCode.Success,
-                ReasonString = pubCompPacket.ReasonString,
-                UserProperties = pubCompPacket.UserProperties ?? EmptyUserProperties
-            };
+            var reasonCode = MqttClientPublishReasonCode.Success;
 
             if (pubRecPacket.ReasonCode != MqttPubRecReasonCode.Success)
             {
                 // Both enums share the same values.
-                result.ReasonCode = (MqttClientPublishReasonCode)pubRecPacket.ReasonCode;
+                reasonCode = (MqttClientPublishReasonCode)pubRecPacket.ReasonCode;
             }
 
-            return result;
+            return new MqttClientPublishResult(pubCompPacket.PacketIdentifier, reasonCode, pubCompPacket.ReasonString, pubCompPacket.UserProperties ?? EmptyUserProperties);
         }
     }
 }

Source/MQTTnet/Formatter/MqttPubRelPacketFactory.cs

@@ -11,7 +11,7 @@ namespace MQTTnet.Formatter
 {
     public sealed class MqttPubRelPacketFactory
     {
-        public MqttPubRelPacket Create(MqttPubRecPacket pubRecPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
+        public MqttPubRelPacket Create(MqttPubRecPacket pubRecPacket, MqttPubRelReasonCode reasonCode)
         {
             if (pubRecPacket == null)
             {
@@ -21,7 +21,7 @@ namespace MQTTnet.Formatter
             return new MqttPubRelPacket
             {
                 PacketIdentifier = pubRecPacket.PacketIdentifier,
-                ReasonCode = (MqttPubRelReasonCode)(int)reasonCode
+                ReasonCode = reasonCode
             };
         }
 

Source/MQTTnet/Server/Internal/MqttClient.cs

@@ -273,7 +273,7 @@ namespace MQTTnet.Server
         {
             // Do not fire the event _ClientAcknowledgedPublishPacket_ here because the QoS 2 process is only finished
             // properly when the client has sent the PUBCOMP packet.
-            var pubRelPacket = _packetFactories.PubRel.Create(pubRecPacket, MqttApplicationMessageReceivedReasonCode.Success);
+            var pubRelPacket = _packetFactories.PubRel.Create(pubRecPacket, MqttPubRelReasonCode.Success);
             Session.EnqueueControlPacket(new MqttPacketBusItem(pubRelPacket));
 
             return CompletedTask.Instance;