Fix discovery fails when using `%hostname%` in a topic (#12710)

CHANGELOG.md

@@ -11,6 +11,10 @@ All notable changes to this project will be documented in this file.
 
 ### Changed
 - Disable PSRAM on unsupported hardware
+- Replace spaces by hyphens in final hostname (#12710)
+
+### Fixed
+- Discovery fails when using ``%hostname%`` in a topic (#12710)
 
 ## [9.5.0.2] 20210714
 ### Added

RELEASENOTES.md

@@ -126,6 +126,7 @@ The latter links can be used for OTA upgrades too like ``OtaUrl http://ota.tasmo
 - Refactor platformio [#12442](https://github.com/arendst/Tasmota/issues/12442)
 - Allow buttons to work in AP normal mode [#12518](https://github.com/arendst/Tasmota/issues/12518)
 - Enable Ping and rule features for any device compiled with more than 1M flash size [#12539](https://github.com/arendst/Tasmota/issues/12539)
+- Replace spaces by hyphens in final hostname [#12710](https://github.com/arendst/Tasmota/issues/12710)
 
 ### Fixed
 - ESP32 core v2.0.0 setting hostname
@@ -142,6 +143,7 @@ The latter links can be used for OTA upgrades too like ``OtaUrl http://ota.tasmo
 - Exception 28 when unable to send MQTT message and a topic name without a slash '/' [#12555](https://github.com/arendst/Tasmota/issues/12555)
 - Wi-Fi initial setup workaround for 11n only routers [#12566](https://github.com/arendst/Tasmota/issues/12566)
 - ESP32 do not use chip temperature sensor as global temperature if external temperature sensor is used [#12630](https://github.com/arendst/Tasmota/issues/12630)
+- Discovery fails when using ``%hostname%`` in a topic [#12710](https://github.com/arendst/Tasmota/issues/12710)
 
 ### Noted
 - ESP32 single core **tasmota32solo1.bin** binary can only be uploaded using the GUI as OTA upload will trigger the watchdog timer. Fixed once https://github.com/espressif/arduino-esp32/pull/5426 is merged.

tasmota/support_tasmota.ino

@@ -77,6 +77,13 @@ char* GetOtaUrl(char *otaurl, size_t otaurl_size)
   return otaurl;
 }
 
+String ResolveToken(const char* input) {
+  String resolved = input;
+  resolved.replace(F("%hostname%"), TasmotaGlobal.hostname);
+  resolved.replace(F("%id%"), NetworkUniqueId());
+  return resolved;
+}
+
 char* GetTopic_P(char *stopic, uint32_t prefix, char *topic, const char* subtopic)
 {
   /* prefix 0 = Cmnd
@@ -120,8 +127,7 @@ char* GetTopic_P(char *stopic, uint32_t prefix, char *topic, const char* subtopi
     fulltopic.replace(FPSTR(MQTT_TOKEN_PREFIX), SettingsText(SET_MQTTPREFIX1 + prefix));
 
     fulltopic.replace(FPSTR(MQTT_TOKEN_TOPIC), (const __FlashStringHelper *)topic);
-    fulltopic.replace(F("%hostname%"), TasmotaGlobal.hostname);
+    fulltopic = ResolveToken(fulltopic.c_str());
-    fulltopic.replace(F("%id%"), NetworkUniqueId());
   }
   fulltopic.replace(F("#"), "");
   fulltopic.replace(F("//"), "/");

tasmota/tasmota.ino

@@ -380,6 +380,12 @@ void setup(void) {
   } else {
     snprintf_P(TasmotaGlobal.hostname, sizeof(TasmotaGlobal.hostname)-1, SettingsText(SET_HOSTNAME));
   }
+  char *s = TasmotaGlobal.hostname;
+  while (*s) {
+    if (' ' == *s) { *s = '_'; }
+    s++;
+  }
+  snprintf_P(TasmotaGlobal.mqtt_topic, sizeof(TasmotaGlobal.mqtt_topic), ResolveToken(TasmotaGlobal.mqtt_topic).c_str());
 
   RtcInit();
   GpioInit();