Fix infinite loop during TLS handshake(Only .NET6) (#583)

Fix infinite loop caused by disconnection during TLS handshake, and the memory exploded instantly.

Author: kenlon

src/DotNetty.Handlers/Tls/TlsHandler.cs

@@ -506,6 +506,13 @@ void Unwrap(
                         }
 
                         int read = currentReadFuture.Result;
+                        
+                        if (read == 0)
+                        {
+                            //Stream closed
+                            return;
+                        }
+                        
                         AddBufferToOutput(outputBuffer, read, output);
                     }
 
@@ -763,4 +770,4 @@ static class TlsHandlerStateExtensions
 
         public static bool HasAny(this TlsHandlerState value, TlsHandlerState testValue) => (value & testValue) != 0;
     }
-}
+}