Fix hostname management (#8626)

* manage hostname with sdk string

Author: d-a-v

Diff for: cores/esp8266/LwipIntf.cpp

@@ -16,6 +16,17 @@ extern "C"
 #include "debug.h"
 #include "LwipIntf.h"
 
+// wifi_station_hostname is SDK's station(=global) hostname location
+// - It is never nullptr but wifi_station_get_hostname()
+//   can return nullptr when STA is down
+// - Because WiFi is started in off mode at boot time,
+//   wifi_station_set/get_hostname() is now no more used
+//   because setting hostname firt does not work anymore
+// - wifi_station_hostname is overwritten by SDK when wifi is
+//   woken up in WiFi::mode()
+//
+extern "C" char* wifi_station_hostname;
+
 // args      | esp order    arduino order
 // ----      + ---------    -------------
 // local_ip  | local_ip     local_ip
@@ -66,7 +77,7 @@ bool LwipIntf::ipAddressReorder(const IPAddress& local_ip, const IPAddress& arg1
 */
 String LwipIntf::hostname(void)
 {
-    return wifi_station_get_hostname();
+    return wifi_station_hostname;
 }
 
 /**
@@ -75,7 +86,7 @@ String LwipIntf::hostname(void)
 */
 const char* LwipIntf::getHostname(void)
 {
-    return wifi_station_get_hostname();
+    return wifi_station_hostname;
 }
 
 /**
@@ -136,20 +147,17 @@ bool LwipIntf::hostname(const char* aHostname)
         DEBUGV("hostname '%s' is not compliant with RFC952\n", aHostname);
     }
 
-    bool ret = wifi_station_set_hostname(aHostname);
-    if (!ret)
-    {
-        DEBUGV("WiFi.hostname(%s): wifi_station_set_hostname() failed\n", aHostname);
-        return false;
-    }
+    bool ret = true;
+
+    strcpy(wifi_station_hostname, aHostname);
 
     // now we should inform dhcp server for this change, using lwip_renew()
     // looping through all existing interface
     // harmless for AP, also compatible with ethernet adapters (to come)
     for (netif* intf = netif_list; intf; intf = intf->next)
     {
         // unconditionally update all known interfaces
-        intf->hostname = wifi_station_get_hostname();
+        intf->hostname = wifi_station_hostname;
 
         if (netif_dhcp_data(intf) != nullptr)
         {

Diff for: libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.cpp

@@ -49,6 +49,9 @@ extern "C" {
 #include "debug.h"
 #include "include/WiFiState.h"
 
+// see comments on wifi_station_hostname in LwipIntf.cpp
+extern "C" char* wifi_station_hostname; // sdk's hostname location
+
 // -----------------------------------------------------------------------------------------------------------------------
 // ------------------------------------------------- Generic WiFi function -----------------------------------------------
 // -----------------------------------------------------------------------------------------------------------------------
@@ -419,7 +422,10 @@ bool ESP8266WiFiGenericClass::mode(WiFiMode_t m) {
         return true;
     }
 
+    char backup_hostname [33] { 0 }; // hostname is 32 chars long (RFC)
+
     if (m != WIFI_OFF && wifi_fpm_get_sleep_type() != NONE_SLEEP_T) {
+        memcpy(backup_hostname, wifi_station_hostname, sizeof(backup_hostname));
         // wifi starts asleep by default
         wifi_fpm_do_wakeup();
         wifi_fpm_close();
@@ -452,6 +458,9 @@ bool ESP8266WiFiGenericClass::mode(WiFiMode_t m) {
         }
     }
 
+    if (backup_hostname[0])
+        memcpy(wifi_station_hostname, backup_hostname, sizeof(backup_hostname));
+
     return ret;
 }
 

Diff for: tests/host/common/user_interface.cpp

@@ -309,10 +309,12 @@ extern "C"
         return wifi_station_get_config(config);
     }
 
-    char        wifi_station_get_hostname_str[128];
-    const char* wifi_station_get_hostname(void)
+    extern "C" char* wifi_station_hostname;  // exists in nonosdk
+    char             wifi_station_hostname_str[33] { "esposix" };
+    char*            wifi_station_hostname = wifi_station_hostname_str;
+    const char*      wifi_station_get_hostname(void)
     {
-        return strcpy(wifi_station_get_hostname_str, "esposix");
+        return wifi_station_hostname;
     }
 
     bool wifi_station_get_reconnect_policy()