From de722e001c7495e6ebb8bce629f50e3faf9dfbb4 Mon Sep 17 00:00:00 2001
From: Gergely Polonkai <gergely@polonkai.eu>
Date: Mon, 18 Jan 2021 10:57:45 +0100
Subject: [PATCH] Set up mDNS in a more fool-proof way

---
 WeatherStation.ino | 48 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 4 deletions(-)

diff --git a/WeatherStation.ino b/WeatherStation.ino
index 7e51758..9cee67b 100644
--- a/WeatherStation.ino
+++ b/WeatherStation.ino
@@ -47,6 +47,9 @@
 # include <Adafruit_BMP085.h>
 #endif // HAVE_BMP180
 
+char *negotiated_hostname = NULL;
+bool hostname_verified = false;
+MDNSResponder::hMDNSService mdns_service = NULL;
 ESP8266WebServer server(80);
 unsigned long last_update = 0;
 
@@ -163,6 +166,42 @@ stop()
     }
 }
 
+bool
+set_station_hostname(const char *hostname)
+{
+    if (hostname) {
+        WiFi.hostname(hostname);
+    }
+
+    return true;
+}
+
+void
+host_probe_result(String hostname, bool result)
+{
+    if (result == true) {
+        set_station_hostname(negotiated_hostname);
+
+        if (!hostname_verified) {
+            hostname_verified = true;
+
+            if (!mdns_service) {
+                mdns_service = MDNS.addService(0, "http", "tcp", 80);
+
+                if (mdns_service) {
+                    MDNS.addServiceTxt(mdns_service, "port#", 80);
+                }
+            }
+        }
+    } else {
+        if (MDNSResponder::indexDomain(negotiated_hostname, "-", 0)) {
+            MDNS.setHostname(negotiated_hostname);
+        } else {
+            Serial.println("Failed to set mDNS hostname");
+        }
+    }
+}
+
 void
 setup()
 {
@@ -183,8 +222,11 @@ setup()
     address.printTo(Serial);
     Serial.println("");
 
-    if (!MDNS.begin(MDNS_NAME)) {
-        Serial.println("Error setting up mDNS responder!");
+    MDNS.setHostProbeResultCallback(host_probe_result);
+
+    if ((!MDNSResponder::indexDomain(negotiated_hostname, 0, MDNS_NAME)) ||
+        (!MDNS.begin(negotiated_hostname))) {
+        Serial.println("Error setting up mDNS!");
 
         stop();
     }
@@ -194,8 +236,6 @@ setup()
 
     server.begin();
 
-    MDNS.addService("http", "tcp", 80);
-
     // Initialize sensors
 #ifdef DHT_TYPE
     dht.begin();