Fix setHostname() after WiFi is already initilised

by @willmmiles

Author: blazoncek

wled00/cfg.cpp

@@ -162,7 +162,8 @@ bool deserializeConfig(JsonObject doc, bool fromFS) {
   // apply WiFi options from above (regardless of fromFS or not)
 #ifdef ARDUINO_ARCH_ESP32
   WiFi.setSleep(!noWifiSleep);
-  WiFi.setHostname(hostName);
+  WiFi.setHostname(hostName); // Sets the hostName in the wifi lib; does not necessarily propagate it to the network interface
+  set_esp_interface_hostname(ESP_IF_WIFI_STA, hostName); // ensure hostName propagates to network interface for DHCP and mDNS
 #else
   WiFi.setPhyMode(force802_3g ? WIFI_PHY_MODE_11G : WIFI_PHY_MODE_11N);
   wifi_set_sleep_type((noWifiSleep) ? NONE_SLEEP_T : MODEM_SLEEP_T);

wled00/network.cpp

@@ -302,6 +302,16 @@ void fillStr2MAC(uint8_t *mac, const char *str) {
   for (int i = 0; i < 6; i++) { *--mac = MAC & 0xFF; MAC >>= 8; }
 }
 
+#ifdef ARDUINO_ARCH_ESP32
+// Shim class to allow access to protected members of WiFiScanClass so we can extend the timeout
+namespace {
+  struct WifiScanAccessor : public WiFiScanClass {
+      static uint32_t& scanStarted() { return WiFiScanClass::_scanStarted; }
+      static uint32_t& scanTimeout() { return WiFiScanClass::_scanTimeout; }
+      static uint16_t& scanCount()  { return WiFiScanClass::_scanCount; };
+  };
+}
+#endif
 
 #ifndef WLED_DISABLE_ESPNOW
 void initESPNow(bool resetAP) {
@@ -389,28 +399,39 @@ int findWiFi(bool doScan) {
 
   if (doScan || status == WIFI_SCAN_FAILED) {
     DEBUG_PRINTF_P(PSTR("WiFi: Scan started. @ %lus\n"), millis()/1000);
-    WiFi.scanNetworks(true);  // start scanning in asynchronous mode (will delete old scan)
-  } else if (status > 0) {    // status contains number of found networks (including duplicate SSIDs with different BSSID)
+    WiFi.disconnect(); // make sure we're not trying to reconnect to a network while scanning
+    status = WiFi.scanNetworks(true);  // start scanning in asynchronous mode (will delete old scan)
+#ifdef ARDUINO_ARCH_ESP32    
+    // the Arduino core can be overly aggressive with its scan timeout if we're busy with the CPU.  Be more generous.
+    if (status == WIFI_SCAN_RUNNING) {
+      WifiScanAccessor::scanTimeout() += 5000;
+    }
+#endif
+  }
+  
+  if (status >= 0) {   // status contains number of found networks (including duplicate SSIDs with different BSSID)
     DEBUG_PRINTF_P(PSTR("WiFi: Found %d SSIDs. @ %lus\n"), status, millis()/1000);
     int rssi = -9999;
     int selected = selectedWiFi;
     for (int o = 0; o < status; o++) {
       DEBUG_PRINTF_P(PSTR(" SSID: %s (BSSID: %s) RSSI: %ddB\n"), WiFi.SSID(o).c_str(), WiFi.BSSIDstr(o).c_str(), WiFi.RSSI(o));
-      for (unsigned n = 0; n < multiWiFi.size(); n++)
+      for (unsigned n = 0; n < multiWiFi.size(); n++) {
         if (!strcmp(WiFi.SSID(o).c_str(), multiWiFi[n].clientSSID)) {
           bool foundBSSID = memcmp(multiWiFi[n].bssid, WiFi.BSSID(o), 6) == 0;
           // find the WiFi with the strongest signal (but keep priority of entry if signal difference is not big)
-          if (foundBSSID || ((int)n < selected && WiFi.RSSI(o) > rssi-10) || WiFi.RSSI(o) > rssi) {
+          // essentially give a bonus to higher priority wifis
+          if (foundBSSID || ((WiFi.RSSI(o) + ((int)n < selected ? 10 : 0)) > rssi)) {
             rssi = foundBSSID ? 0 : WiFi.RSSI(o); // RSSI is only ever negative
             selected = n;
           }
           break;
         }
+      }
     }
     DEBUG_PRINTF_P(PSTR("WiFi: Selected SSID: %s RSSI: %ddB\n"), multiWiFi[selected].clientSSID, rssi);
     return selected+1;
   }
-  //DEBUG_PRINT(F("WiFi scan running."));
+  //DEBUG_PRINTF_P(PSTR("WiFi scan running: %d. @ %lus\n"), status, millis()/1000);
   return status; // scan is still running or there was an error
 }
 

wled00/network.h

@@ -3,6 +3,13 @@
 #ifndef WLED_NETWORK_H
 #define WLED_NETWORK_H
 
+#ifdef ARDUINO_ARCH_ESP32
+// Declare internal Arduino library function to work around the fact that WiFi.setHostname() does not propagate the
+// hostname to the network interface if it's been previously used.  The underlying ESP-IDF layer supports this just
+// fine; it's an oversight in the Arduino layer that we can work around by calling the internal function directly.
+esp_err_t set_esp_interface_hostname(esp_interface_t interface, const char * hostname);
+#endif
+
 #ifndef WLED_DISABLE_ESPNOW
 typedef struct {
   char    magic[4];     // enough to store "WLED"

wled00/set.cpp

@@ -73,7 +73,8 @@ void handleSettingsSet(AsyncWebServerRequest *request, byte subPage)
   #ifdef WLED_USE_ETHERNET
     ETH.setHostname(hostName);
   #endif
-    WiFi.setHostname(hostName);
+    WiFi.setHostname(hostName); // Sets the hostName in the wifi lib; does not necessarily propagate it to the network interface
+    set_esp_interface_hostname(ESP_IF_WIFI_STA, hostName); // ensure hostName propagates to network interface for DHCP and mDNS
 #else
     WiFi.hostname(hostName);
 #endif