improve exceptions in case of corrupt packages close pipes after exception occoured to avoid lingering connections should fix #788

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -145,6 +145,13 @@ namespace MQTTnet.AspNetCore
                     }
                 }
             }
+            catch (Exception e)
+            {
+                // completing the cannels makes sure that there is no more data read after a protocol error
+                _input?.Complete(e);
+                _output?.Complete(e);
+                throw;
+            }
             finally
             {
                 ReadingPacketCompletedCallback?.Invoke();

Source/MQTTnet.AspnetCore/SpanBasedMqttPacketBodyReader.cs

@@ -117,6 +117,10 @@ namespace MQTTnet.AspNetCore
             var span = _buffer.Span;
             var length = BinaryPrimitives.ReadUInt16BigEndian(span.Slice(_offset));
 
+            if (Length < _offset + length)
+            {
+                throw new MqttProtocolViolationException($"Expected at least {_offset + 2 + length} bytes but there are only {Length} bytes");
+            }
             var result = span.Slice(_offset + 2, length);
             _offset += 2 + length;
             return result;

Source/MQTTnet.AspnetCore/SpanBasedMqttPacketWriter.cs

@@ -10,6 +10,11 @@ namespace MQTTnet.AspNetCore
     {
         readonly ArrayPool<byte> _pool = ArrayPool<byte>.Create();
 
+        public SpanBasedMqttPacketWriter()
+        {
+            Reset(0);
+        }
+
         byte[] _buffer;
         int _position;
 

Source/MQTTnet/Formatter/MqttPacketBodyReader.cs

@@ -134,7 +134,7 @@ namespace MQTTnet.Formatter
         {
             if (_length < _offset + length)
             {
-                throw new ArgumentOutOfRangeException(nameof(_buffer), $"Expected at least {_offset + length} bytes but there are only {_length} bytes");
+                throw new MqttProtocolViolationException($"Expected at least {_offset + length} bytes but there are only {_length} bytes");
             }
         }
 

Source/MQTTnet/Formatter/MqttPacketFormatterAdapter.cs

@@ -120,6 +120,14 @@ namespace MQTTnet.Formatter
         {
             if (receivedMqttPacket == null) throw new ArgumentNullException(nameof(receivedMqttPacket));
 
+            if (receivedMqttPacket.Body.Length < 7)
+            {
+                // 2 byte protocol name length
+                // at least 4 byte protocol name
+                // 1 byte protocol level
+                throw new MqttProtocolViolationException("Mqtt Connect packet must have at least 7 bytes");
+            }
+
             var protocolName = receivedMqttPacket.Body.ReadStringWithLengthPrefix();
             var protocolLevel = receivedMqttPacket.Body.ReadByte();