static void FilterRetainedApplicationMessages(
IList <MqttApplicationMessage> retainedApplicationMessages,
CreateSubscriptionResult createSubscriptionResult,
SubscribeResult subscribeResult)
{
for (var index = retainedApplicationMessages.Count - 1; index >= 0; index--)
{
var retainedApplicationMessage = retainedApplicationMessages[index];
if (retainedApplicationMessage == null)
{
continue;
}
if (createSubscriptionResult.Subscription.RetainHandling == MqttRetainHandling.DoNotSendOnSubscribe)
{
// This is a MQTT V5+ feature.
continue;
}
if (createSubscriptionResult.Subscription.RetainHandling == MqttRetainHandling.SendAtSubscribeIfNewSubscriptionOnly && !createSubscriptionResult.IsNewSubscription)
{
// This is a MQTT V5+ feature.
continue;
}
if (MqttTopicFilterComparer.Compare(retainedApplicationMessage.Topic, createSubscriptionResult.Subscription.Topic) != MqttTopicFilterCompareResult.IsMatch)
{
continue;
}
var retainedMessageMatch = new MqttRetainedMessageMatch
{
ApplicationMessage = retainedApplicationMessage,
SubscriptionQualityOfServiceLevel = createSubscriptionResult.Subscription.GrantedQualityOfServiceLevel
};
if (subscribeResult.RetainedMessages == null)
{
subscribeResult.RetainedMessages = new List <MqttRetainedMessageMatch>();
}
subscribeResult.RetainedMessages.Add(retainedMessageMatch);
// Clear the retained message from the list because the client should receive every message only
// one time even if multiple subscriptions affect them.
retainedApplicationMessages[index] = null;
}
}
public async Task <SubscribeResult> Subscribe(MqttSubscribePacket subscribePacket, CancellationToken cancellationToken)
{
if (subscribePacket == null)
{
throw new ArgumentNullException(nameof(subscribePacket));
}
var retainedApplicationMessages = await _retainedMessagesManager.GetMessages().ConfigureAwait(false);
var result = new SubscribeResult
{
ReasonCodes = new List <MqttSubscribeReasonCode>(subscribePacket.TopicFilters.Count)
};
var addedSubscriptions = new List <string>();
// The topic filters are order by its QoS so that the higher QoS will win over a
// lower one.
foreach (var originalTopicFilter in subscribePacket.TopicFilters.OrderByDescending(f => f.QualityOfServiceLevel))
{
var subscriptionEventArgs = await InterceptSubscribe(originalTopicFilter, cancellationToken).ConfigureAwait(false);
var finalTopicFilter = subscriptionEventArgs.TopicFilter;
var processSubscription = subscriptionEventArgs.ProcessSubscription && subscriptionEventArgs.Response.ReasonCode <= MqttSubscribeReasonCode.GrantedQoS2;
result.UserProperties = subscriptionEventArgs.UserProperties;
result.ReasonString = subscriptionEventArgs.ReasonString;
result.ReasonCodes.Add(subscriptionEventArgs.Response.ReasonCode);
if (subscriptionEventArgs.CloseConnection)
{
// When any of the interceptor calls leads to a connection close the connection
// must be closed. So do not revert to false!
result.CloseConnection = true;
}
if (!processSubscription || string.IsNullOrEmpty(finalTopicFilter.Topic))
{
continue;
}
var createSubscriptionResult = CreateSubscription(finalTopicFilter, subscribePacket.SubscriptionIdentifier, subscriptionEventArgs.Response.ReasonCode);
addedSubscriptions.Add(finalTopicFilter.Topic);
if (_eventContainer.ClientSubscribedTopicEvent.HasHandlers)
{
var eventArgs = new ClientSubscribedTopicEventArgs
{
ClientId = _session.Id,
TopicFilter = finalTopicFilter
};
await _eventContainer.ClientSubscribedTopicEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
}
FilterRetainedApplicationMessages(retainedApplicationMessages, createSubscriptionResult, result);
}
_subscriptionChangedNotification?.OnSubscriptionsAdded(_session, addedSubscriptions);
return(result);
}
