Accept multiple SubscriptionIdentifiers for PUBLISH packets.

Source/MQTTnet/Formatter/V5/MqttV500DataConverter.cs

@@ -33,13 +33,14 @@ namespace MQTTnet.Formatter.V5
                     MessageExpiryInterval = applicationMessage.MessageExpiryInterval,
                     PayloadFormatIndicator = applicationMessage.PayloadFormatIndicator,
                     ResponseTopic = applicationMessage.ResponseTopic,
-                    SubscriptionIdentifier = applicationMessage.SubscriptionIdentifier,
+                    SubscriptionIdentifiers = applicationMessage.SubscriptionIdentifiers,
                     TopicAlias = applicationMessage.TopicAlias
                 }
             };
 
             if (applicationMessage.UserProperties != null)
             {
+                packet.Properties.UserProperties = new List<MqttUserProperty>();
                 packet.Properties.UserProperties.AddRange(applicationMessage.UserProperties);
             }
 
@@ -67,7 +68,7 @@ namespace MQTTnet.Formatter.V5
                 ContentType = publishPacket.Properties?.ContentType,
                 CorrelationData = publishPacket.Properties?.CorrelationData,
                 MessageExpiryInterval = publishPacket.Properties?.MessageExpiryInterval,
-                SubscriptionIdentifier = publishPacket.Properties?.SubscriptionIdentifier,
+                SubscriptionIdentifiers = publishPacket.Properties?.SubscriptionIdentifiers,
                 TopicAlias = publishPacket.Properties?.TopicAlias,
                 PayloadFormatIndicator = publishPacket.Properties?.PayloadFormatIndicator,
                 UserProperties = publishPacket.Properties?.UserProperties ?? new List<MqttUserProperty>()

Source/MQTTnet/Formatter/V5/MqttV500PacketDecoder.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using MQTTnet.Adapter;
 using MQTTnet.Exceptions;
@@ -117,7 +118,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -155,7 +156,12 @@ namespace MQTTnet.Formatter.V5
                     }
                     else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.SubscriptionIdentifier)
                     {
-                        packet.WillMessage.SubscriptionIdentifier = propertiesReader.ReadSubscriptionIdentifier();
+                        if (packet.WillMessage.SubscriptionIdentifiers == null)
+                        {
+                            packet.WillMessage.SubscriptionIdentifiers = new List<uint>();
+                        }
+
+                        packet.WillMessage.SubscriptionIdentifiers.Add(propertiesReader.ReadSubscriptionIdentifier());
                     }
                     else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.ContentType)
                     {
@@ -168,7 +174,12 @@ namespace MQTTnet.Formatter.V5
                     }
                     else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                     {
-                        propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                        if (packet.WillMessage.UserProperties == null)
+                        {
+                            packet.WillMessage.UserProperties = new List<MqttUserProperty>();
+                        }
+
+                        propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                     }
                     else
                     {
@@ -271,7 +282,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -309,7 +320,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -339,7 +350,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -389,7 +400,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -421,7 +432,7 @@ namespace MQTTnet.Formatter.V5
             {
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -456,7 +467,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -530,7 +541,12 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.SubscriptionIdentifier)
                 {
-                    packet.Properties.SubscriptionIdentifier = propertiesReader.ReadSubscriptionIdentifier();
+                    if (packet.Properties.SubscriptionIdentifiers == null)
+                    {
+                        packet.Properties.SubscriptionIdentifiers = new List<uint>();
+                    }
+
+                    packet.Properties.SubscriptionIdentifiers.Add(propertiesReader.ReadSubscriptionIdentifier());
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.ContentType)
                 {
@@ -538,7 +554,12 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -581,7 +602,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -619,7 +640,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -657,7 +678,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -695,7 +716,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -740,7 +761,7 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {

Source/MQTTnet/Formatter/V5/MqttV500PacketEncoder.cs

@@ -150,7 +150,7 @@ namespace MQTTnet.Formatter.V5
                 willPropertiesWriter.WriteTopicAlias(packet.WillMessage.TopicAlias);
                 willPropertiesWriter.WriteResponseTopic(packet.WillMessage.ResponseTopic);
                 willPropertiesWriter.WriteCorrelationData(packet.WillMessage.CorrelationData);
-                willPropertiesWriter.WriteSubscriptionIdentifier(packet.WillMessage.SubscriptionIdentifier);
+                willPropertiesWriter.WriteSubscriptionIdentifiers(packet.WillMessage.SubscriptionIdentifiers);
                 willPropertiesWriter.WriteContentType(packet.WillMessage.ContentType);
                 willPropertiesWriter.WriteUserProperties(packet.WillMessage.UserProperties);
                 
@@ -258,7 +258,7 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteTopicAlias(packet.Properties.TopicAlias);
                 propertiesWriter.WriteResponseTopic(packet.Properties.ResponseTopic);
                 propertiesWriter.WriteCorrelationData(packet.Properties.CorrelationData);
-                propertiesWriter.WriteSubscriptionIdentifier(packet.Properties.SubscriptionIdentifier);
+                propertiesWriter.WriteSubscriptionIdentifiers(packet.Properties.SubscriptionIdentifiers);
                 propertiesWriter.WriteContentType(packet.Properties.ContentType);
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }

Source/MQTTnet/Formatter/V5/MqttV500PropertiesReader.cs

@@ -42,7 +42,7 @@ namespace MQTTnet.Formatter.V5
             return true;
         }
 
-        public void FillUserProperties(List<MqttUserProperty> userProperties)
+        public void AddUserPropertyTo(List<MqttUserProperty> userProperties)
         {
             if (userProperties == null) throw new ArgumentNullException(nameof(userProperties));
 
@@ -67,17 +67,17 @@ namespace MQTTnet.Formatter.V5
             return _body.ReadWithLengthPrefix();
         }
 
-        public bool? ReadRetainAvailable()
+        public bool ReadRetainAvailable()
         {
             return _body.ReadBoolean();
         }
 
-        public uint? ReadSessionExpiryInterval()
+        public uint ReadSessionExpiryInterval()
         {
             return _body.ReadFourByteInteger();
         }
 
-        public ushort? ReadReceiveMaximum()
+        public ushort ReadReceiveMaximum()
         {
             return _body.ReadTwoByteInteger();
         }
@@ -92,17 +92,17 @@ namespace MQTTnet.Formatter.V5
             return _body.ReadStringWithLengthPrefix();
         }
 
-        public ushort? ReadTopicAliasMaximum()
+        public ushort ReadTopicAliasMaximum()
         {
             return _body.ReadTwoByteInteger();
         }
 
-        public uint? ReadMaximumPacketSize()
+        public uint ReadMaximumPacketSize()
         {
             return _body.ReadFourByteInteger();
         }
 
-        public ushort? ReadServerKeepAlive()
+        public ushort ReadServerKeepAlive()
         {
             return _body.ReadTwoByteInteger();
         }
@@ -112,22 +112,22 @@ namespace MQTTnet.Formatter.V5
             return _body.ReadStringWithLengthPrefix();
         }
 
-        public bool? ReadSharedSubscriptionAvailable()
+        public bool ReadSharedSubscriptionAvailable()
         {
             return _body.ReadBoolean();
         }
 
-        public bool? ReadSubscriptionIdentifiersAvailable()
+        public bool ReadSubscriptionIdentifiersAvailable()
         {
             return _body.ReadBoolean();
         }
 
-        public bool? ReadWildcardSubscriptionAvailable()
+        public bool ReadWildcardSubscriptionAvailable()
         {
             return _body.ReadBoolean();
         }
 
-        public uint? ReadSubscriptionIdentifier()
+        public uint ReadSubscriptionIdentifier()
         {
             return _body.ReadVariableLengthInteger();
         }
@@ -137,12 +137,12 @@ namespace MQTTnet.Formatter.V5
             return (MqttPayloadFormatIndicator)_body.ReadByte();
         }
 
-        public uint? ReadMessageExpiryInterval()
+        public uint ReadMessageExpiryInterval()
         {
             return _body.ReadFourByteInteger();
         }
 
-        public ushort? ReadTopicAlias()
+        public ushort ReadTopicAlias()
         {
             return _body.ReadTwoByteInteger();
         }
@@ -162,17 +162,17 @@ namespace MQTTnet.Formatter.V5
             return _body.ReadStringWithLengthPrefix();
         }
 
-        public uint? ReadWillDelayInterval()
+        public uint ReadWillDelayInterval()
         {
             return _body.ReadFourByteInteger();
         }
 
-        public bool? RequestResponseInformation()
+        public bool RequestResponseInformation()
         {
             return _body.ReadBoolean();
         }
 
-        public bool? RequestProblemInformation()
+        public bool RequestProblemInformation()
         {
             return _body.ReadBoolean();
         }

Source/MQTTnet/Formatter/V5/MqttV500PropertiesWriter.cs

@@ -80,6 +80,19 @@ namespace MQTTnet.Formatter.V5
             WriteAsVariableLengthInteger(MqttPropertyId.SubscriptionIdentifier, value);
         }
 
+        public void WriteSubscriptionIdentifiers(IEnumerable<uint> value)
+        {
+            if (value == null)
+            {
+                return;
+            }
+
+            foreach (var subscriptionIdentifier in value)
+            {
+                WriteAsVariableLengthInteger(MqttPropertyId.SubscriptionIdentifier, subscriptionIdentifier);
+            }
+        }
+
         public void WriteTopicAlias(ushort? value)
         {
             Write(MqttPropertyId.TopicAlias, value);

Source/MQTTnet/MqttApplicationMessage.cs

@@ -28,6 +28,6 @@ namespace MQTTnet
 
         public byte[] CorrelationData { get; set; }
 
-        public uint? SubscriptionIdentifier { get; set; }
+        public List<uint> SubscriptionIdentifiers { get; set; }
     }
 }

Source/MQTTnet/MqttApplicationMessageBuilder.cs

@@ -18,7 +18,7 @@ namespace MQTTnet
         private string _responseTopic;
         private byte[] _correlationData;
         private ushort? _topicAlias;
-        private uint? _subscriptionIdentifier;
+        private List<uint> _subscriptionIdentifiers;
         private uint? _messageExpiryInterval;
         private MqttPayloadFormatIndicator? _payloadFormatIndicator;
         private List<MqttUserProperty> _userProperties;
@@ -43,7 +43,7 @@ namespace MQTTnet
             {
                 _payload = payload.ToArray();
             }
-            
+
             return this;
         }
 
@@ -176,7 +176,12 @@ namespace MQTTnet
         /// </summary>
         public MqttApplicationMessageBuilder WithSubscriptionIdentifier(uint subscriptionIdentifier)
         {
-            _subscriptionIdentifier = subscriptionIdentifier;
+            if (_subscriptionIdentifiers == null)
+            {
+                _subscriptionIdentifiers = new List<uint>();
+            }
+
+            _subscriptionIdentifiers.Add(subscriptionIdentifier);
             return this;
         }
 
@@ -215,16 +220,12 @@ namespace MQTTnet
                 ResponseTopic = _responseTopic,
                 CorrelationData = _correlationData,
                 TopicAlias = _topicAlias,
-                SubscriptionIdentifier = _subscriptionIdentifier,
+                SubscriptionIdentifiers = _subscriptionIdentifiers,
                 MessageExpiryInterval = _messageExpiryInterval,
-                PayloadFormatIndicator = _payloadFormatIndicator
+                PayloadFormatIndicator = _payloadFormatIndicator,
+                UserProperties = _userProperties
             };
 
-            if (_userProperties?.Any() == true)
-            {
-                applicationMessage.UserProperties = _userProperties;
-            }
-            
             return applicationMessage;
         }
     }

Source/MQTTnet/Packets/MqttPublishPacketProperties.cs

@@ -15,9 +15,9 @@ namespace MQTTnet.Packets
 
         public byte[] CorrelationData { get; set; }
 
-        public List<MqttUserProperty> UserProperties { get; } = new List<MqttUserProperty>();
+        public List<MqttUserProperty> UserProperties { get; set; }
 
-        public uint? SubscriptionIdentifier { get; set; }
+        public List<uint> SubscriptionIdentifiers { get; set; }
 
         public string ContentType { get; set; }
     }

Tests/MQTTnet.Core.Tests/MqttPacketSerializer_Tests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text;
@@ -234,7 +235,7 @@ namespace MQTTnet.Tests
         [TestMethod]
         public void SerializeV500_MqttPublishPacket()
         {
-            var prop = new MqttPublishPacketProperties();
+            var prop = new MqttPublishPacketProperties {UserProperties = new List<MqttUserProperty>()};
 
             prop.ResponseTopic = "/Response";