From d2d07543b2a3d46fbc2f100ef94c60e816a1f139 Mon Sep 17 00:00:00 2001
From: Mike <7153163+hackbar@users.noreply.github.com>
Date: Tue, 15 Jan 2019 17:26:51 -0800
Subject: [PATCH 1/3] Do an MDNS resolve before using the cached host.

MDNS shouldn't be aggressively cached, since the IP could change. This
makes using DHCP for the host a lot easier.
---
 sonoff/xdrv_02_mqtt.ino | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sonoff/xdrv_02_mqtt.ino b/sonoff/xdrv_02_mqtt.ino
index 1d3c3a4b8..ae84d1940 100644
--- a/sonoff/xdrv_02_mqtt.ino
+++ b/sonoff/xdrv_02_mqtt.ino
@@ -516,7 +516,7 @@ void MqttReconnect(void)
 #ifndef USE_MQTT_TLS
 #ifdef USE_DISCOVERY
 #ifdef MQTT_HOST_DISCOVERY
-  if (!strlen(Settings.mqtt_host) && !MqttDiscoverServer()) { return; }
+  if (!MqttDiscoverServer() && !strlen(Settings.mqtt_host)) { return; }
 #endif  // MQTT_HOST_DISCOVERY
 #endif  // USE_DISCOVERY
 #endif  // USE_MQTT_TLS

From 5e06ae1d8197b17069c92a3b7e61f4a0621d8c6c Mon Sep 17 00:00:00 2001
From: Mike <7153163+hackbar@users.noreply.github.com>
Date: Tue, 15 Jan 2019 18:08:28 -0800
Subject: [PATCH 2/3] Do MDNS even if TLS is enabled.

I imagine this was disabled due to memory issues, but this seems to work
fine on a Sonoff Basic.
---
 sonoff/xdrv_02_mqtt.ino | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/sonoff/xdrv_02_mqtt.ino b/sonoff/xdrv_02_mqtt.ino
index ae84d1940..58204dd9a 100644
--- a/sonoff/xdrv_02_mqtt.ino
+++ b/sonoff/xdrv_02_mqtt.ino
@@ -513,13 +513,11 @@ void MqttReconnect(void)
   mqtt_retry_counter = Settings.mqtt_retry;
   global_state.mqtt_down = 1;
 
-#ifndef USE_MQTT_TLS
 #ifdef USE_DISCOVERY
 #ifdef MQTT_HOST_DISCOVERY
   if (!MqttDiscoverServer() && !strlen(Settings.mqtt_host)) { return; }
 #endif  // MQTT_HOST_DISCOVERY
 #endif  // USE_DISCOVERY
-#endif  // USE_MQTT_TLS
 
   char *mqtt_user = NULL;
   char *mqtt_pwd = NULL;
@@ -585,13 +583,11 @@ void MqttCheck(void)
     if (!MqttIsConnected()) {
       global_state.mqtt_down = 1;
       if (!mqtt_retry_counter) {
-#ifndef USE_MQTT_TLS
 #ifdef USE_DISCOVERY
 #ifdef MQTT_HOST_DISCOVERY
         if (!strlen(Settings.mqtt_host) && !mdns_begun) { return; }
 #endif  // MQTT_HOST_DISCOVERY
 #endif  // USE_DISCOVERY
-#endif  // USE_MQTT_TLS
         MqttReconnect();
       } else {
         mqtt_retry_counter--;

From 838b113fa34a128c90bf26a66c60cb9886706ed0 Mon Sep 17 00:00:00 2001
From: Mike <7153163+hackbar@users.noreply.github.com>
Date: Tue, 15 Jan 2019 21:48:07 -0800
Subject: [PATCH 3/3] Add a define for mDNS hostname to connect to for MQTT.

---
 sonoff/xdrv_02_mqtt.ino | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/sonoff/xdrv_02_mqtt.ino b/sonoff/xdrv_02_mqtt.ino
index 58204dd9a..4321cb7b0 100644
--- a/sonoff/xdrv_02_mqtt.ino
+++ b/sonoff/xdrv_02_mqtt.ino
@@ -220,9 +220,19 @@ boolean MqttDiscoverServer(void)
   AddLog(LOG_LEVEL_INFO);
 
   if (n > 0) {
-    // Note: current strategy is to get the first MQTT service (even when many are found)
+    #ifdef MDNS_HOSTNAME
+    for (int i = 0; i < n; i++) {
+      if (!strcmp(MDNS.hostname(i).c_str(), MDNS_HOSTNAME)) {
+         snprintf_P(Settings.mqtt_host, sizeof(Settings.mqtt_host), MDNS.IP(i).toString().c_str());
+         Settings.mqtt_port = MDNS.port(i);
+         break;  // stop at the first matching record
+      }
+    }
+    #else
+    // If the hostname isn't set, use the first record found.
     snprintf_P(Settings.mqtt_host, sizeof(Settings.mqtt_host), MDNS.IP(0).toString().c_str());
     Settings.mqtt_port = MDNS.port(0);
+    #endif  // MDNS_HOSTNAME
 
     snprintf_P(log_data, sizeof(log_data), PSTR(D_LOG_MDNS D_MQTT_SERVICE_FOUND " %s, " D_IP_ADDRESS " %s, " D_PORT " %d"),
       MDNS.hostname(0).c_str(), Settings.mqtt_host, Settings.mqtt_port);