/// <summary>
/// Save session for a client (all related subscriptions)
/// </summary>
/// <param name="clientId">Client Id to save subscriptions</param>
/// <param name="clientSession">Client session with inflight messages</param>
/// <param name="subscriptions">Subscriptions to save</param>
public void SaveSession(string clientId, MqttClientSession clientSession, List<MqttSubscription> subscriptions)
{
MqttBrokerSession session = null;
// session doesn't exist
if (!this.sessions.ContainsKey(clientId))
{
// create new session
session = new MqttBrokerSession();
session.ClientId = clientId;
// add to sessions list
this.sessions.Add(clientId, session);
}
else
{
// get existing session
session = this.sessions[clientId];
}
// null reference to disconnected client
session.Client = null;
// update subscriptions
session.Subscriptions = new List<MqttSubscription>();
foreach (MqttSubscription subscription in subscriptions)
{
session.Subscriptions.Add(new MqttSubscription(subscription.ClientId, subscription.Topic, subscription.QosLevel, null));
}
// update inflight messages
session.InflightMessages = new Hashtable();
foreach (MqttMsgContext msgContext in clientSession.InflightMessages.Values)
{
session.InflightMessages.Add(msgContext.Key, msgContext);
}
}
void Client_MqttMsgConnected(object sender, MqttMsgConnectEventArgs e)
{
// [v3.1.1] session present flag
bool sessionPresent = false;
// [v3.1.1] generated client id for client who provides client id zero bytes length
string clientId = null;
MqttClient client = (MqttClient)sender;
mqttBridge.OnClientConnect(client, e);
// verify message to determine CONNACK message return code to the client
byte returnCode = this.MqttConnectVerify(e.Message);
// [v3.1.1] if client id is zero length, the broker assigns a unique identifier to it
clientId = (e.Message.ClientId.Length != 0) ? e.Message.ClientId : Guid.NewGuid().ToString();
// connection "could" be accepted
if (returnCode == MqttMsgConnack.CONN_ACCEPTED)
{
// check if there is a client already connected with same client Id
MqttClient clientConnected = this.GetClient(clientId);
// force connection close to the existing client (MQTT protocol)
if (clientConnected != null)
{
this.CloseClient(clientConnected);
}
}
try
{
// connection accepted, load (if exists) client session
if (returnCode == MqttMsgConnack.CONN_ACCEPTED)
{
// check if not clean session and try to recovery a session
if (!e.Message.CleanSession)
{
// create session for the client
MqttClientSession clientSession = new MqttClientSession(clientId);
// get session for the connected client
MqttBrokerSession session = this.sessionManager.GetSession(clientId);
// set inflight queue into the client session
if (session != null)
{
clientSession.InflightMessages = session.InflightMessages;
// [v3.1.1] session present flag
if (client.ProtocolVersion == MqttProtocolVersion.Version_3_1_1)
sessionPresent = true;
}
// send CONNACK message to the client
client.Connack(e.Message, returnCode, clientId, sessionPresent);
// load/inject session to the client
client.LoadSession(clientSession);
if (session != null)
{
// set reference to connected client into the session
session.Client = client;
// there are saved subscriptions
if (session.Subscriptions != null)
{
// register all subscriptions for the connected client
foreach (MqttSubscription subscription in session.Subscriptions)
{
this.subscriberManager.Subscribe(subscription.Topic, subscription.QosLevel, client);
// publish retained message on the current subscription
this.publisherManager.PublishRetaind(subscription.Topic, clientId);
}
}
// there are saved outgoing messages
if (session.OutgoingMessages.Count > 0)
{
// publish outgoing messages for the session
this.publisherManager.PublishSession(session.ClientId);
}
}
}
// requested clean session
else
{
// send CONNACK message to the client
client.Connack(e.Message, returnCode, clientId, sessionPresent);
this.sessionManager.ClearSession(clientId);
}
}
else
{
// send CONNACK message to the client
client.Connack(e.Message, returnCode, clientId, sessionPresent);
}
}
catch (MqttCommunicationException)
{
this.CloseClient(client);
}
}