void TryMaintainConnection(MqttClientConnection connection, DateTime now)
{
try
{
if (connection.Status != MqttClientConnectionStatus.Running)
{
// The connection is already dead or just created so there is no need to check it.
return;
}
if (connection.ConnectPacket.KeepAlivePeriod == 0)
{
// The keep alive feature is not used by the current connection.
return;
}
if (connection.IsReadingPacket)
{
// The connection is currently reading a (large) packet. So it is obviously
// doing something and thus "connected".
return;
}
// Values described here: [MQTT-3.1.2-24].
// If the client sends 5 sec. the server will allow up to 7.5 seconds.
// If the client sends 1 sec. the server will allow up to 1.5 seconds.
var maxDurationWithoutPacket = connection.ConnectPacket.KeepAlivePeriod * 1.5D;
var secondsWithoutPackage = (now - connection.LastPacketReceivedTimestamp).TotalSeconds;
if (secondsWithoutPackage < maxDurationWithoutPacket)
{
// A packet was received before the timeout is affected.
return;
}
_logger.Warning(null, "Client '{0}': Did not receive any packet or keep alive signal.", connection.ClientId);
// Execute the disconnection in background so that the keep alive monitor can continue
// with checking other connections.
// We do not need to wait for the task so no await is needed.
// Also the internal state of the connection must be swapped to "Finalizing" because the
// next iteration of the keep alive timer happens.
var _ = connection.StopAsync(MqttDisconnectReasonCode.KeepAliveTimeout);
}
catch (Exception exception)
{
_logger.Error(exception, "Client {0}: Unhandled exception while checking keep alive timeouts.", connection.ClientId);
}
}
async Task <MqttApplicationMessageInterceptorContext> InterceptApplicationMessageAsync(IMqttServerApplicationMessageInterceptor interceptor, MqttClientConnection senderConnection, MqttApplicationMessage applicationMessage)
{
string senderClientId;
IDictionary <object, object> sessionItems;
var messageIsFromServer = senderConnection == null;
if (messageIsFromServer)
{
senderClientId = _options.ClientId;
sessionItems = _serverSessionItems;
}
else
{
senderClientId = senderConnection.ClientId;
sessionItems = senderConnection.Session.Items;
}
var interceptorContext = new MqttApplicationMessageInterceptorContext(senderClientId, sessionItems, applicationMessage);
await interceptor.InterceptApplicationMessagePublishAsync(interceptorContext).ConfigureAwait(false);
return(interceptorContext);
}
public void DispatchApplicationMessage(MqttApplicationMessage applicationMessage, MqttClientConnection sender)
{
if (applicationMessage == null)
{
throw new ArgumentNullException(nameof(applicationMessage));
}
_messageQueue.Add(new MqttEnqueuedApplicationMessage(applicationMessage, sender));
}