MQTT autodiscover and autoconnect features

code/espurna/config/general.h

@@ -334,6 +334,8 @@ PROGMEM const char* const custom_reset_string[] = {
 #define MQTT_SSL_FINGERPRINT    ""
 
 #define MQTT_ENABLED            0           // Do not enable MQTT connection by default
+#define MQTT_AUTOCONNECT        1           // If enabled and MDNS_SUPPORT=1 will perform an autodiscover and
+                                            // autoconnect to the first MQTT broker found if none defined
 #define MQTT_SERVER             ""          // Default MQTT broker address
 #define MQTT_PORT               1883        // MQTT broker port
 #define MQTT_TOPIC              "/test/switch/{identifier}"     // Default MQTT base topic
@@ -342,7 +344,7 @@ PROGMEM const char* const custom_reset_string[] = {
 #define MQTT_KEEPALIVE          30          // MQTT keepalive value
 #define MQTT_RECONNECT_DELAY    10000       // Try to reconnect after 10s
 #define MQTT_TRY_INTERVAL       30000       // Timeframe for disconnect retries
-#define MQTT_MAX_TRIES          10          // After these many retries during the previous MQTT_TRY_INTERVAL the board will reset
+#define MQTT_MAX_TRIES          5           // After these many retries during the previous MQTT_TRY_INTERVAL the board will reset
 #define MQTT_SKIP_RETAINED      1           // Skip retained messages on connection
 #define MQTT_SKIP_TIME          1000        // Skip messages for 1 second anter connection
 

code/espurna/mqtt.ino

@@ -7,6 +7,7 @@ Copyright (C) 2016-2017 by Xose Pérez <xose dot perez at gmail dot com>
 */
 
 #include <ESP8266WiFi.h>
+#include <ESP8266mDNS.h>
 #include <ArduinoJson.h>
 #include <vector>
 #include <Ticker.h>
@@ -448,6 +449,27 @@ void mqttConfigure() {
 
 }
 
+#ifdef MDNS_SUPPORT
+boolean mqttDiscover() {
+
+    int count = MDNS.queryService("mqtt", "tcp");
+    DEBUG_MSG_P("[MQTT] MQTT brokers found: %d\n", count);
+
+    for (int i=0; i<count; i++) {
+
+        DEBUG_MSG_P("[MQTT] Broker at %s:%d\n", MDNS.IP(i).toString().c_str(), MDNS.port(i));
+
+        if ((i==0) && (getSetting("mqttServer").length() == 0)) {
+            setSetting("mqttServer", MDNS.IP(i).toString());
+            setSetting("mqttPort", MDNS.port(i));
+            mqttEnabled(MQTT_AUTOCONNECT);
+        }
+
+    }
+
+}
+#endif  // MDNS_SUPPORT
+
 void mqttSetup() {
     #if MQTT_USE_ASYNC
         mqtt.onConnect([](bool sessionPresent) {

code/espurna/wifi.ino

@@ -231,6 +231,7 @@ void wifiSetup() {
                 if (MDNS.begin(WiFi.getMode() == WIFI_AP ? APP_NAME : (char *) WiFi.hostname().c_str())) {
                     MDNS.addService("http", "tcp", getSetting("webPort", WEB_PORT).toInt());
     	            DEBUG_MSG_P(PSTR("[MDNS] OK\n"));
+                    if (code == MESSAGE_CONNECTED) mqttDiscover();
     	        } else {
     	            DEBUG_MSG_P(PSTR("[MDNS] FAIL\n"));
     	        }