private MqttMsgBase WaitForPubrel(
MqttConnection connection,
MqttMsgContext msgContext,
MqttMsgBase msgInflight,
ref bool msgReceivedProcessed)
{
// QoS 2, waiting for PUBREL of a PUBREC message sent
if (msgContext.Flow != MqttMsgFlow.ToAcknowledge)
{
return(null);
}
if (!connection.InternalQueue.TryPeek(out MqttMsgBase msgReceived))
{
return(null);
}
InternalEvent internalEvent;
// it is a PUBREL message
if (msgReceived != null && msgReceived.Type == MqttMsgBase.MQTT_MSG_PUBREL_TYPE)
{
if (msgReceived.MessageId == msgInflight.MessageId)
{
// received message processed
connection.InternalQueue.TryDequeue(out MqttMsgBase dequeuedMsg);
msgReceivedProcessed = true;
outgoingMessageHandler.Pubcomp(connection, msgInflight.MessageId);
internalEvent = new InternalEvent(msgInflight);
// notify published message from broker and acknowledged
connection.EnqueueInternalEvent(internalEvent);
// PUBREL received (and PUBCOMP sent) for PUBLISH message with QoS Level 2, remove from session state
if (msgInflight.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE && connection.Session != null &&
connection.Session.InflightMessages.ContainsKey(msgContext.Key))
{
connection.Session.InflightMessages.TryRemove(
msgContext.Key,
out MqttMsgContext contextToBeRemoved);
}
}
else
{
// re-enqueue message
connection.EnqueueInflight(msgContext);
}
}
else
{
connection.EnqueueInflight(msgContext);
}
return(msgReceived);
}
private int SendPubrel(
MqttConnection connection,
MqttMsgContext msgContext,
MqttMsgBase msgInflight,
int timeout)
{
// QoS 2, PUBREL message to send to broker, state change to wait PUBCOMP
if (msgContext.Flow == MqttMsgFlow.ToPublish)
{
msgContext.State = MqttMsgState.WaitForPubcomp;
msgContext.Timestamp = Environment.TickCount;
msgContext.Attempt++;
// retry ? set dup flag [v3.1.1] no needed
if (connection.ProtocolVersion == MqttProtocolVersion.Version_3_1 && msgContext.Attempt > 1)
{
outgoingMessageHandler.Pubrel(connection, msgInflight.MessageId, true);
}
else
{
outgoingMessageHandler.Pubrel(connection, msgInflight.MessageId, false);
}
// update timeout : minimum between delay (based on current message sent) or current timeout
timeout = connection.Settings.DelayOnRetry < timeout ? connection.Settings.DelayOnRetry : timeout;
// re-enqueue message
connection.EnqueueInflight(msgContext);
}
return(timeout);
}
private int HandleQueuedQos1SendSubscribeAndSendUnsubscribe(
MqttConnection connection,
MqttMsgContext msgContext,
MqttMsgBase msgInflight,
int timeout)
{
InternalEvent internalEvent;
// QoS 1, PUBLISH or SUBSCRIBE/UNSUBSCRIBE message to send to broker, state change to wait PUBACK or SUBACK/UNSUBACK
if (msgContext.Flow == MqttMsgFlow.ToPublish)
{
msgContext.Timestamp = Environment.TickCount;
msgContext.Attempt++;
if (msgInflight.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE)
{
// PUBLISH message to send, wait for PUBACK
msgContext.State = MqttMsgState.WaitForPuback;
// retry ? set dup flag [v3.1.1] only for PUBLISH message
if (msgContext.Attempt > 1)
{
msgInflight.DupFlag = true;
}
}
else if (msgInflight.Type == MqttMsgBase.MQTT_MSG_SUBSCRIBE_TYPE)
{
// SUBSCRIBE message to send, wait for SUBACK
msgContext.State = MqttMsgState.WaitForSuback;
}
else if (msgInflight.Type == MqttMsgBase.MQTT_MSG_UNSUBSCRIBE_TYPE)
{
// UNSUBSCRIBE message to send, wait for UNSUBACK
msgContext.State = MqttMsgState.WaitForUnsuback;
}
outgoingMessageHandler.Send(connection, msgInflight);
// update timeout : minimum between delay (based on current message sent) or current timeout
timeout = connection.Settings.DelayOnRetry < timeout ? connection.Settings.DelayOnRetry : timeout;
// re-enqueue message (I have to re-analyze for receiving PUBACK, SUBACK or UNSUBACK)
connection.EnqueueInflight(msgContext);
}
// QoS 1, PUBLISH message received from broker to acknowledge, send PUBACK
else if (msgContext.Flow == MqttMsgFlow.ToAcknowledge)
{
outgoingMessageHandler.Puback(connection, msgInflight.MessageId);
internalEvent = new InternalEvent(msgInflight);
// notify published message from broker and acknowledged
connection.EnqueueInternalEvent(internalEvent);
}
return(timeout);
}
private int HandleQueuedQos2(
MqttConnection connection,
MqttMsgContext msgContext,
MqttMsgBase msgInflight,
int timeout)
{
// QoS 2, PUBLISH message to send to broker, state change to wait PUBREC
if (msgContext.Flow == MqttMsgFlow.ToPublish)
{
msgContext.Timestamp = Environment.TickCount;
msgContext.Attempt++;
msgContext.State = MqttMsgState.WaitForPubrec;
// retry ? set dup flag
if (msgContext.Attempt > 1)
{
msgInflight.DupFlag = true;
}
outgoingMessageHandler.Send(connection, msgInflight);
// update timeout : minimum between delay (based on current message sent) or current timeout
timeout = connection.Settings.DelayOnRetry < timeout ? connection.Settings.DelayOnRetry : timeout;
// re-enqueue message (I have to re-analyze for receiving PUBREC)
connection.EnqueueInflight(msgContext);
}
// QoS 2, PUBLISH message received from broker to acknowledge, send PUBREC, state change to wait PUBREL
else if (msgContext.Flow == MqttMsgFlow.ToAcknowledge)
{
msgContext.State = MqttMsgState.WaitForPubrel;
outgoingMessageHandler.Pubrec(connection, msgInflight.MessageId);
// re-enqueue message (I have to re-analyze for receiving PUBREL)
connection.EnqueueInflight(msgContext);
}
return(timeout);
}
private void EnqueueInflight(MqttConnection connection, MqttMsgBase msg, MqttMsgFlow flow)
{
// enqueue is needed (or not)
var enqueue = true;
// if it is a PUBLISH message with QoS Level 2
if (msg.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE && msg.QosLevel == MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE)
{
// if it is a PUBLISH message already received (it is in the inflight queue), the publisher
// re-sent it because it didn't received the PUBREC. In connection case, we have to re-send PUBREC
// NOTE : I need to find on message id and flow because the broker could be publish/received
// to/from client and message id could be the same (one tracked by broker and the other by client)
var msgCtxFinder = new MqttMsgContextFinder(msg.MessageId, MqttMsgFlow.ToAcknowledge);
var msgCtx = (MqttMsgContext)connection.InflightQueue.FirstOrDefault(msgCtxFinder.Find);
// the PUBLISH message is alredy in the inflight queue, we don't need to re-enqueue but we need
// to change state to re-send PUBREC
if (msgCtx != null)
{
msgCtx.State = MqttMsgState.QueuedQos2;
msgCtx.Flow = MqttMsgFlow.ToAcknowledge;
enqueue = false;
}
}
if (enqueue)
{
// set a default state
var state = MqttMsgState.QueuedQos0;
// based on QoS level, the messages flow between broker and client changes
switch (msg.QosLevel)
{
// QoS Level 0
case MqttMsgBase.QOS_LEVEL_AT_MOST_ONCE:
state = MqttMsgState.QueuedQos0;
break;
// QoS Level 1
case MqttMsgBase.QOS_LEVEL_AT_LEAST_ONCE:
state = MqttMsgState.QueuedQos1;
break;
// QoS Level 2
case MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE:
state = MqttMsgState.QueuedQos2;
break;
}
// [v3.1.1] SUBSCRIBE and UNSUBSCRIBE aren't "officially" QOS = 1
// so QueuedQos1 state isn't valid for them
if (msg.Type == MqttMsgBase.MQTT_MSG_SUBSCRIBE_TYPE)
{
state = MqttMsgState.SendSubscribe;
}
else if (msg.Type == MqttMsgBase.MQTT_MSG_UNSUBSCRIBE_TYPE)
{
state = MqttMsgState.SendUnsubscribe;
}
// queue message context
var msgContext = new MqttMsgContext()
{
Message = msg,
State = state,
Flow = flow,
Attempt = 0
};
// enqueue message and unlock send thread
connection.EnqueueInflight(msgContext);
// PUBLISH message
if (msg.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE)
{
if (msgContext.Flow == MqttMsgFlow.ToPublish &&
(msg.QosLevel == MqttMsgBase.QOS_LEVEL_AT_LEAST_ONCE ||
msg.QosLevel == MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE))
{
if (connection.Session != null)
{
connection.Session.InflightMessages.TryAdd(msgContext.Key, msgContext);
}
}
// to acknowledge and QoS level 2
else if (msgContext.Flow == MqttMsgFlow.ToAcknowledge &&
msg.QosLevel == MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE)
{
if (connection.Session != null)
{
connection.Session.InflightMessages.TryAdd(msgContext.Key, msgContext);
}
}
}
}
}
private MqttMsgBase WaitForPubcomp(
MqttConnection connection,
MqttMsgContext msgContext,
MqttMsgBase msgInflight,
ref bool msgReceivedProcessed,
ref int timeout)
{
// QoS 2, waiting for PUBCOMP of a PUBREL message sent
if (msgContext.Flow != MqttMsgFlow.ToPublish)
{
return(null);
}
if (!connection.InternalQueue.TryPeek(out MqttMsgBase msgReceived))
{
return(null);
}
var acknowledge = false;
InternalEvent internalEvent;
// it is a PUBCOMP message
if (msgReceived.Type == MqttMsgBase.MQTT_MSG_PUBCOMP_TYPE)
{
// PUBCOMP message for the current message
if (msgReceived.MessageId == msgInflight.MessageId)
{
connection.InternalQueue.TryDequeue(out MqttMsgBase dequeuedMsg);
acknowledge = true;
msgReceivedProcessed = true;
internalEvent = new PublishedInternalEvent(msgReceived, true);
// notify received acknowledge from broker of a published message
connection.EnqueueInternalEvent(internalEvent);
// PUBCOMP received for PUBLISH message with QoS Level 2, remove from session state
if (msgInflight.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE && connection.Session != null &&
connection.Session.InflightMessages.ContainsKey(msgContext.Key))
{
connection.Session.InflightMessages.TryRemove(
msgContext.Key,
out MqttMsgContext contextToBeRemoved);
}
}
}
// it is a PUBREC message
else if (msgReceived.Type == MqttMsgBase.MQTT_MSG_PUBREC_TYPE)
{
// another PUBREC message for the current message due to a retransmitted PUBLISH
// I'm in waiting for PUBCOMP, so I can discard connection PUBREC
if (msgReceived.MessageId == msgInflight.MessageId)
{
connection.InternalQueue.TryDequeue(out MqttMsgBase dequeuedMsg);
acknowledge = true;
msgReceivedProcessed = true;
// re-enqueue message
connection.EnqueueInflight(msgContext);
}
}
// current message not acknowledged
if (!acknowledge)
{
var delta = Environment.TickCount - msgContext.Timestamp;
// check timeout for receiving PUBCOMP since PUBREL was sent
if (delta >= connection.Settings.DelayOnRetry)
{
// max retry not reached, resend
if (msgContext.Attempt < connection.Settings.AttemptsOnRetry)
{
msgContext.State = MqttMsgState.SendPubrel;
// re-enqueue message
connection.EnqueueInflight(msgContext);
// update timeout (0 -> reanalyze queue immediately)
timeout = 0;
}
else
{
// PUBCOMP not received, PUBREL retries failed, need to remove from session inflight messages too
if (connection.Session != null &&
connection.Session.InflightMessages.ContainsKey(msgContext.Key))
{
connection.Session.InflightMessages.TryRemove(
msgContext.Key,
out MqttMsgContext contextToBeRemoved);
}
// if PUBCOMP for a PUBLISH message not received after retries, raise event for not published
internalEvent = new PublishedInternalEvent(msgInflight, false);
// notify not received acknowledge from broker and message not published
connection.EnqueueInternalEvent(internalEvent);
}
}
else
{
// re-enqueue message
connection.EnqueueInflight(msgContext);
// update timeout
var msgTimeout = connection.Settings.DelayOnRetry - delta;
timeout = msgTimeout < timeout ? msgTimeout : timeout;
}
}
return(msgReceived);
}
private MqttMsgBase HandleWaitForPubrec(
MqttConnection connection,
MqttMsgContext msgContext,
MqttMsgBase msgInflight,
ref bool msgReceivedProcessed,
ref int timeout)
{
// QoS 2, waiting for PUBREC of a PUBLISH message sent
if (msgContext.Flow != MqttMsgFlow.ToPublish)
{
return(null);
}
if (!connection.InternalQueue.TryPeek(out MqttMsgBase msgReceived))
{
return(null);
}
var acknowledge = false;
InternalEvent internalEvent;
// it is a PUBREC message
if (msgReceived.Type == MqttMsgBase.MQTT_MSG_PUBREC_TYPE)
{
if (msgReceived.MessageId == msgInflight.MessageId)
{
// received message processed
connection.InternalQueue.TryDequeue(out MqttMsgBase dequeuedMsg);
acknowledge = true;
msgReceivedProcessed = true;
outgoingMessageHandler.Pubrel(connection, msgInflight.MessageId, false);
msgContext.State = MqttMsgState.WaitForPubcomp;
msgContext.Timestamp = Environment.TickCount;
msgContext.Attempt = 1;
// update timeout : minimum between delay (based on current message sent) or current timeout
timeout = connection.Settings.DelayOnRetry < timeout ? connection.Settings.DelayOnRetry : timeout;
// re-enqueue message
connection.EnqueueInflight(msgContext);
}
}
// current message not acknowledged
if (!acknowledge)
{
var delta = Environment.TickCount - msgContext.Timestamp;
// check timeout for receiving PUBREC since PUBLISH was sent
if (delta >= connection.Settings.DelayOnRetry)
{
// max retry not reached, resend
if (msgContext.Attempt < connection.Settings.AttemptsOnRetry)
{
msgContext.State = MqttMsgState.QueuedQos2;
// re-enqueue message
connection.EnqueueInflight(msgContext);
// update timeout (0 -> reanalyze queue immediately)
timeout = 0;
}
else
{
// PUBREC not received in time, PUBLISH retries failed, need to remove from session inflight messages too
if (connection.Session != null &&
connection.Session.InflightMessages.ContainsKey(msgContext.Key))
{
connection.Session.InflightMessages.TryRemove(
msgContext.Key,
out MqttMsgContext contextToBeRemoved);
}
// if PUBREC for a PUBLISH message not received after retries, raise event for not published
internalEvent = new PublishedInternalEvent(msgInflight, false);
// notify not received acknowledge from broker and message not published
connection.EnqueueInternalEvent(internalEvent);
}
}
else
{
// re-enqueue message
connection.EnqueueInflight(msgContext);
// update timeout
var msgTimeout = connection.Settings.DelayOnRetry - delta;
timeout = msgTimeout < timeout ? msgTimeout : timeout;
}
}
return(msgReceived);
}
private MqttMsgBase HandleWaitForPubackSubackUbsuback(
MqttConnection connection,
MqttMsgContext msgContext,
MqttMsgBase msgInflight,
ref bool msgReceivedProcessed,
ref int timeout)
{
// QoS 1, waiting for PUBACK of a PUBLISH message sent or
// waiting for SUBACK of a SUBSCRIBE message sent or
// waiting for UNSUBACK of a UNSUBSCRIBE message sent or
if (msgContext.Flow != MqttMsgFlow.ToPublish)
{
return(null);
}
if (!connection.InternalQueue.TryPeek(out MqttMsgBase msgReceived))
{
return(null);
}
var acknowledge = false;
InternalEvent internalEvent;
// PUBACK message or SUBACK/UNSUBACK message for the current message
if (msgReceived.Type == MqttMsgBase.MQTT_MSG_PUBACK_TYPE &&
msgInflight.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE &&
msgReceived.MessageId == msgInflight.MessageId ||
msgReceived.Type == MqttMsgBase.MQTT_MSG_SUBACK_TYPE &&
msgInflight.Type == MqttMsgBase.MQTT_MSG_SUBSCRIBE_TYPE &&
msgReceived.MessageId == msgInflight.MessageId ||
msgReceived.Type == MqttMsgBase.MQTT_MSG_UNSUBACK_TYPE &&
msgInflight.Type == MqttMsgBase.MQTT_MSG_UNSUBSCRIBE_TYPE &&
msgReceived.MessageId == msgInflight.MessageId)
{
// received message processed
connection.InternalQueue.TryDequeue(out MqttMsgBase dequeuedMsg);
acknowledge = true;
msgReceivedProcessed = true;
// if PUBACK received, confirm published with flag
if (msgReceived.Type == MqttMsgBase.MQTT_MSG_PUBACK_TYPE)
{
internalEvent = new PublishedInternalEvent(msgReceived, true);
}
else
{
internalEvent = new InternalEvent(msgReceived);
}
// notify received acknowledge from broker of a published message or subscribe/unsubscribe message
connection.EnqueueInternalEvent(internalEvent);
// PUBACK received for PUBLISH message with QoS Level 1, remove from session state
if (msgInflight.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE && connection.Session != null &&
connection.Session.InflightMessages.ContainsKey(msgContext.Key))
{
connection.Session.InflightMessages.TryRemove(msgContext.Key, out MqttMsgContext contextToBeRemoved);
}
}
// current message not acknowledged, no PUBACK or SUBACK/UNSUBACK or not equal messageid
if (!acknowledge)
{
var delta = Environment.TickCount - msgContext.Timestamp;
// check timeout for receiving PUBACK since PUBLISH was sent or
// for receiving SUBACK since SUBSCRIBE was sent or
// for receiving UNSUBACK since UNSUBSCRIBE was sent
if (delta >= connection.Settings.DelayOnRetry)
{
// max retry not reached, resend
if (msgContext.Attempt < connection.Settings.AttemptsOnRetry)
{
msgContext.State = MqttMsgState.QueuedQos1;
// re-enqueue message
connection.EnqueueInflight(msgContext);
// update timeout (0 -> reanalyze queue immediately)
timeout = 0;
}
else
{
// if PUBACK for a PUBLISH message not received after retries, raise event for not published
if (msgInflight.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE)
{
// PUBACK not received in time, PUBLISH retries failed, need to remove from session inflight messages too
if (connection.Session != null &&
connection.Session.InflightMessages.ContainsKey(msgContext.Key))
{
connection.Session.InflightMessages.TryRemove(
msgContext.Key,
out MqttMsgContext contextToBeRemoved);
}
internalEvent = new PublishedInternalEvent(msgInflight, false);
// notify not received acknowledge from broker and message not published
connection.EnqueueInternalEvent(internalEvent);
}
// NOTE : not raise events for SUBACK or UNSUBACK not received
// for the user no event raised means subscribe/unsubscribe failed
}
}
else
{
// re-enqueue message (I have to re-analyze for receiving PUBACK, SUBACK or UNSUBACK)
connection.EnqueueInflight(msgContext);
// update timeout
var msgTimeout = connection.Settings.DelayOnRetry - delta;
timeout = msgTimeout < timeout ? msgTimeout : timeout;
}
}
return(msgReceived);
}