fix confusing disconnect event (#83)

* Fix confusing disconnect event

* Do dispatch TCP connection failure event

* Fix confusing code line due to bad cherry-pick

Author: Adam5Wu

src/AsyncMqttClient.cpp

@@ -340,22 +340,19 @@ void AsyncMqttClient::_onConnect(AsyncClient* client) {
 
 void AsyncMqttClient::_onDisconnect(AsyncClient* client) {
   (void)client;
-  AsyncMqttClientDisconnectReason reason;
+  if (!_disconnectFlagged) {
+    AsyncMqttClientDisconnectReason reason;
 
-  if (_connectPacketNotEnoughSpace) {
-    reason = AsyncMqttClientDisconnectReason::ESP8266_NOT_ENOUGH_SPACE;
-  } else if (_tlsBadFingerprint) {
-    reason = AsyncMqttClientDisconnectReason::TLS_BAD_FINGERPRINT;
-  } else {
-    reason = AsyncMqttClientDisconnectReason::TCP_DISCONNECTED;
+    if (_connectPacketNotEnoughSpace) {
+      reason = AsyncMqttClientDisconnectReason::ESP8266_NOT_ENOUGH_SPACE;
+    } else if (_tlsBadFingerprint) {
+      reason = AsyncMqttClientDisconnectReason::TLS_BAD_FINGERPRINT;
+    } else {
+      reason = AsyncMqttClientDisconnectReason::TCP_DISCONNECTED;
+    }
+    for (auto callback : _onDisconnectUserCallbacks) callback(reason);
   }
-
   _clear();
-
-  for (auto callback : _onDisconnectUserCallbacks) callback(reason);
-
-  _connectPacketNotEnoughSpace = false;
-  _tlsBadFingerprint = false;
 }
 
 void AsyncMqttClient::_onError(AsyncClient* client, int8_t error) {
@@ -488,8 +485,8 @@ void AsyncMqttClient::_onConnAck(bool sessionPresent, uint8_t connectReturnCode)
     _connected = true;
     for (auto callback : _onConnectUserCallbacks) callback(sessionPresent);
   } else {
-    _clear();
     for (auto callback : _onDisconnectUserCallbacks) callback(static_cast<AsyncMqttClientDisconnectReason>(connectReturnCode));
+    _disconnectFlagged = true;
   }
 }
 
@@ -657,6 +654,8 @@ void AsyncMqttClient::_sendAcks() {
 }
 
 bool AsyncMqttClient::_sendDisconnect() {
+  if (!_connected) return true;
+
   const uint8_t neededSpace = 2;
 
   SEMAPHORE_TAKE(false);