Update comments, release notes, version.

Author: chkr1011

.github/workflows/ReleaseNotes.md

@@ -1,2 +1,3 @@
+* [Core] MQTT Packets being sent over web socket transport are now setting the web socket frame boundaries correctly (#1499).
 * [Client] Keep alive mechanism now uses the configured timeout value from the options (thanks to @Stannieman, #1495).
-* [Core] MQTT Packets being sent over web socket transport are now setting the web socket frame boundaries correctly (#1499).
+* [Server] A DISCONNECT packet is no longer sent to MQTT clients < 5.0.0 (thanks to @logicaloud, #1506).

.github/workflows/ci.yml

@@ -3,7 +3,7 @@ name: CI
 on: [push, pull_request]
 
 env:
- VERSION: "4.1.0.${{github.run_number}}"
+ VERSION: "4.1.1.${{github.run_number}}"
 
 jobs:
  build:

Source/MQTTnet/Server/Internal/MqttClient.cs

@@ -147,15 +147,20 @@ public async Task StopAsync(MqttDisconnectReasonCode reason)
  {
  IsRunning = false;
 
- // Potentially send disconnect reason to MQTT 5 clients
-
- if (ChannelAdapter.PacketFormatterAdapter.ProtocolVersion == MqttProtocolVersion.V500 && reason != MqttDisconnectReasonCode.NormalDisconnection) 
+ // Sending DISCONNECT packets from the server to the client is only supported when using MQTTv5+.
+ if (ChannelAdapter.PacketFormatterAdapter.ProtocolVersion == MqttProtocolVersion.V500)
  {
- // Is is very important to send the DISCONNECT packet here BEFORE cancelling the
- // token because the entire connection is closed (disposed) as soon as the cancellation
- // token is cancelled. To there is no chance that the DISCONNECT packet will ever arrive
- // at the client!
- await TrySendDisconnectPacket(reason).ConfigureAwait(false);
+ // The Client or Server MAY send a DISCONNECT packet before closing the Network Connection.
+ // This library does not sent a DISCONNECT packet for a normal disconnection. Maybe adding
+ // a configuration option is requested in the future.
+ if (reason != MqttDisconnectReasonCode.NormalDisconnection)
+ {
+ // Is is very important to send the DISCONNECT packet here BEFORE cancelling the
+ // token because the entire connection is closed (disposed) as soon as the cancellation
+ // token is cancelled. To there is no chance that the DISCONNECT packet will ever arrive
+ // at the client!
+ await TrySendDisconnectPacket(reason).ConfigureAwait(false);
+ }
  }
 
  StopInternal();