fix: prevent MQTT disconnect loop by reusing Paho client on reconnect

mqttStart() called MQTTAsync_create()/MQTTClient_create() on every
invocation, including reconnects from mqttEvery5Seconds(). This leaked
the old Paho client handle without destroying it. The old client's
internal threads would eventually reconnect using the same MQTT
clientID, causing the broker to disconnect the new client ("session
taken over"), creating a permanent connect/disconnect loop.

Fix: create the Paho client once (guarded by mqttClientCreated flag)
and reuse it on reconnect, matching the ESP32 implementation pattern.
Properly destroy the client in mqttStop().

Affects: hasp_mqtt_paho_async.cpp (Linux, macOS, Windows async builds)
         hasp_mqtt_paho_single.cpp (Windows synchronous builds)
Does not affect: ESP32/ESP8266/STM32 (different MQTT implementations)

Fixes #1005

Made-with: Cursor

Author: alvarolobato

src/mqtt/hasp_mqtt_paho_async.cpp

@@ -83,6 +83,7 @@ uint16_t mqttPort         = MQTT_PORT;
 
 MQTTAsync mqtt_client;
 
+static bool mqttClientCreated = false;
 static bool mqttConnecting = false;
 static bool mqttConnected  = false;
 
@@ -361,18 +362,21 @@ void mqttStart()
     int rc;
     int ch;
 
-    if((rc = MQTTAsync_create(&mqtt_client, mqttServer.c_str(), haspDevice.get_hostname(), MQTTCLIENT_PERSISTENCE_NONE,
-                              NULL)) != MQTTASYNC_SUCCESS) {
-        LOG_ERROR(TAG_MQTT, "Failed to create client, return code %d", rc);
-        rc = EXIT_FAILURE;
-        return;
-    }
+    if(!mqttClientCreated) {
+        if((rc = MQTTAsync_create(&mqtt_client, mqttServer.c_str(), haspDevice.get_hostname(), MQTTCLIENT_PERSISTENCE_NONE,
+                                  NULL)) != MQTTASYNC_SUCCESS) {
+            LOG_ERROR(TAG_MQTT, "Failed to create client, return code %d", rc);
+            rc = EXIT_FAILURE;
+            return;
+        }
 
-    if((rc = MQTTAsync_setCallbacks(mqtt_client, mqtt_client, connlost, mqtt_message_arrived, NULL)) !=
-       MQTTASYNC_SUCCESS) {
-        LOG_ERROR(TAG_MQTT, "Failed to set callbacks, return code %d", rc);
-        rc = EXIT_FAILURE;
-        return;
+        if((rc = MQTTAsync_setCallbacks(mqtt_client, mqtt_client, connlost, mqtt_message_arrived, NULL)) !=
+           MQTTASYNC_SUCCESS) {
+            LOG_ERROR(TAG_MQTT, "Failed to set callbacks, return code %d", rc);
+            rc = EXIT_FAILURE;
+            return;
+        }
+        mqttClientCreated = true;
     }
 
     mqttEnabled = mqttServer.length() > 0 && mqttPort > 0;
@@ -410,6 +414,8 @@ void mqttStart()
 
 void mqttStop()
 {
+    if(!mqttClientCreated) return;
+
     int rc;
     MQTTAsync_disconnectOptions disc_opts = MQTTAsync_disconnectOptions_initializer;
     disc_opts.onSuccess                   = onDisconnect;
@@ -418,6 +424,8 @@ void mqttStop()
         LOG_ERROR(TAG_MQTT, "Failed to disconnect, return code %d", rc);
         rc = EXIT_FAILURE;
     }
+    MQTTAsync_destroy(&mqtt_client);
+    mqttClientCreated = false;
 }
 
 void mqttSetup()

src/mqtt/hasp_mqtt_paho_single.cpp

@@ -80,6 +80,7 @@ uint16_t mqttPort         = MQTT_PORT;
 
 MQTTClient mqtt_client;
 
+static bool mqttClientCreated = false;
 int disc_finished = 0;
 int subscribed    = 0;
 int connected     = 0;
@@ -300,18 +301,21 @@ void mqttStart()
     int ch;
 
     LOG_DEBUG(TAG_MQTT, "%s %d", __FILE__, __LINE__);
-    if((rc = MQTTClient_create(&mqtt_client, mqttServer.c_str(), haspDevice.get_hostname(), MQTTCLIENT_PERSISTENCE_NONE,
-                               NULL)) != MQTTCLIENT_SUCCESS) {
-        LOG_ERROR(TAG_MQTT, "Failed to create client, return code %d", rc);
-        rc = EXIT_FAILURE;
-        return;
-    }
+    if(!mqttClientCreated) {
+        if((rc = MQTTClient_create(&mqtt_client, mqttServer.c_str(), haspDevice.get_hostname(), MQTTCLIENT_PERSISTENCE_NONE,
+                                   NULL)) != MQTTCLIENT_SUCCESS) {
+            LOG_ERROR(TAG_MQTT, "Failed to create client, return code %d", rc);
+            rc = EXIT_FAILURE;
+            return;
+        }
 
-    if((rc = MQTTClient_setCallbacks(mqtt_client, mqtt_client, connlost, mqtt_message_arrived, NULL)) !=
-       MQTTCLIENT_SUCCESS) {
-        LOG_ERROR(TAG_MQTT, "Failed to set callbacks, return code %d", rc);
-        rc = EXIT_FAILURE;
-        return;
+        if((rc = MQTTClient_setCallbacks(mqtt_client, mqtt_client, connlost, mqtt_message_arrived, NULL)) !=
+           MQTTCLIENT_SUCCESS) {
+            LOG_ERROR(TAG_MQTT, "Failed to set callbacks, return code %d", rc);
+            rc = EXIT_FAILURE;
+            return;
+        }
+        mqttClientCreated = true;
     }
 
     LOG_DEBUG(TAG_MQTT, "%s %d", __FILE__, __LINE__);
@@ -350,6 +354,8 @@ void mqttStart()
 
 void mqttStop()
 {
+    if(!mqttClientCreated) return;
+
     int rc;
     // MQTTClient_disconnectOptions disc_opts = MQTTClient_disconnectOptions_initializer;
     // disc_opts.onSuccess                    = onDisconnect;
@@ -358,6 +364,8 @@ void mqttStop()
         LOG_ERROR(TAG_MQTT, "Failed to disconnect, return code %d", rc);
         rc = EXIT_FAILURE;
     }
+    MQTTClient_destroy(&mqtt_client);
+    mqttClientCreated = false;
 }
 
 void mqttSetup()