async Task <MqttApplicationMessageInterceptorContext> InterceptApplicationMessageAsync(
IMqttServerApplicationMessageInterceptor interceptor,
MqttClientConnection clientConnection,
MqttApplicationMessage applicationMessage)
{
string senderClientId;
IDictionary <object, object> sessionItems;
var messageIsFromServer = clientConnection == null;
if (messageIsFromServer)
{
senderClientId = _options.ClientId;
sessionItems = _serverSessionItems;
}
else
{
senderClientId = clientConnection.ClientId;
sessionItems = clientConnection.Session.Items;
}
var interceptorContext = new MqttApplicationMessageInterceptorContext
{
ClientId = senderClientId,
SessionItems = sessionItems,
AcceptPublish = true,
ApplicationMessage = applicationMessage,
CloseConnection = false
};
await interceptor.InterceptApplicationMessagePublishAsync(interceptorContext).ConfigureAwait(false);
return(interceptorContext);
}
void TryMaintainConnection(MqttClientConnection connection, DateTime now)
{
try
{
if (!connection.IsRunning)
{
// The connection is already dead or just created so there is no need to check it.
return;
}
if (connection.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.KeepAlivePeriod * 1.5D;
var secondsWithoutPackage = (now - connection.Statistics.LastPacketSentTimestamp).TotalSeconds;
if (secondsWithoutPackage < maxDurationWithoutPacket)
{
// A packet was received before the timeout is affected.
return;
}
_logger.Warning("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(MqttClientDisconnectReason.KeepAliveTimeout);
}
catch (Exception exception)
{
_logger.Error(exception, "Client {0}: Unhandled exception while checking keep alive timeouts.", connection.ClientId);
}
}
public async Task HandleClientConnectionAsync(IMqttChannelAdapter channelAdapter,
CancellationToken cancellationToken)
{
MqttClientConnection clientConnection = null;
try
{
var connectPacket = await ReceiveConnectPacket(channelAdapter, cancellationToken).ConfigureAwait(false);
if (connectPacket == null)
{
// Nothing was received in time etc.
return;
}
MqttConnAckPacket connAckPacket;
var connectionValidatorContext =
await ValidateConnection(connectPacket, channelAdapter).ConfigureAwait(false);
if (connectionValidatorContext.ReasonCode != MqttConnectReasonCode.Success)
{
// Send failure response here without preparing a session!
connAckPacket =
channelAdapter.PacketFormatterAdapter.DataConverter.CreateConnAckPacket(
connectionValidatorContext);
await channelAdapter.SendPacketAsync(connAckPacket, cancellationToken).ConfigureAwait(false);
return;
}
connAckPacket =
channelAdapter.PacketFormatterAdapter.DataConverter.CreateConnAckPacket(connectionValidatorContext);
// Pass connAckPacket so that IsSessionPresent flag can be set if the client session already exists
clientConnection = await CreateClientConnection(connectPacket, connAckPacket, channelAdapter,
connectionValidatorContext.SessionItems).ConfigureAwait(false);
await channelAdapter.SendPacketAsync(connAckPacket, cancellationToken).ConfigureAwait(false);
await _eventDispatcher.SafeNotifyClientConnectedAsync(connectPacket, channelAdapter)
.ConfigureAwait(false);
await clientConnection.RunAsync().ConfigureAwait(false);
}
catch (OperationCanceledException)
{
}
catch (Exception exception)
{
_logger.Error(exception, exception.Message);
}
finally
{
if (clientConnection != null)
{
if (clientConnection.ClientId != null)
{
// in case it is a takeover _clientConnections already contains the new connection
if (!clientConnection.IsTakenOver)
{
lock (_clientConnections)
{
_clientConnections.Remove(clientConnection.ClientId);
}
if (!_options.EnablePersistentSessions)
{
await DeleteSessionAsync(clientConnection.ClientId).ConfigureAwait(false);
}
}
}
var endpoint = clientConnection.Endpoint;
if (clientConnection.ClientId != null && !clientConnection.IsTakenOver)
{
// The event is fired at a separate place in case of a handover!
await _eventDispatcher.SafeNotifyClientDisconnectedAsync(
clientConnection.ClientId,
clientConnection.IsCleanDisconnect
?MqttClientDisconnectType.Clean
: MqttClientDisconnectType.NotClean,
endpoint).ConfigureAwait(false);
}
}
clientConnection?.Dispose();
await channelAdapter.DisconnectAsync(_options.DefaultCommunicationTimeout, CancellationToken.None)
.ConfigureAwait(false);
}
}
public void DispatchApplicationMessage(MqttApplicationMessage applicationMessage, MqttClientConnection sender)
{
if (applicationMessage == null)
{
throw new ArgumentNullException(nameof(applicationMessage));
}
_messageQueue.Add(new MqttPendingApplicationMessage(applicationMessage, sender));
}