Retry MQTT connection indefinitely until it works

src/wlan.cpp

@@ -17,16 +17,25 @@ void connect_wlan(Config *config) {
         delay(1000);
         Serial.print(".");
     }
+    Serial.println("");
     Serial.println("WiFi connected");
 }
 
 void connect_mqtt(PubSubClient &client, Config *config) {
-    if (!client.connected())
+    bool connection;
     client.setServer(config->mqtt_host, config->mqtt_port);
-    if (client.connect(config->device_id, config->mqtt_user,
-                       config->mqtt_password)) {
+
+    while (!client.connected()) {
+        connection = client.connect(config->device_id, config->mqtt_user,
+                                    config->mqtt_password);
+        if (connection) {
             Serial.println("MQTT connected");
             client.subscribe(config->topic);
+        } else {
+            Serial.println("MQTT failed to connect");
+            Serial.println(client.state());
+            delay(5000);
+        }
     }
 }