Optimize hostname variable size

Author: RetiredWizard

ports/espressif/common-hal/wifi/__init__.c

@@ -16,8 +16,6 @@
 #include "py/gc.h"
 #include "py/mpstate.h"
 #include "py/runtime.h"
-#include "py/objstr.h"
-#include "py/objint.h"
 
 #include "components/esp_wifi/include/esp_wifi.h"
 
@@ -42,6 +40,8 @@ wifi_radio_obj_t common_hal_wifi_radio_obj;
 #include "nvs_flash.h"
 #endif
 
+#define MAC_ADDRESS_LENGTH 6
+
 static const char *TAG = "CP wifi";
 
 static void schedule_background_on_cp_core(void *arg) {
@@ -200,8 +200,8 @@ void common_hal_wifi_init(bool user_initiated) {
         return;
     }
     // set the default lwip_local_hostname
-    char cpy_default_hostname[80];
-    uint8_t mac[6];
+    char cpy_default_hostname[strlen(CIRCUITPY_BOARD_ID)+(MAC_ADDRESS_LENGTH*2)+6];
+    uint8_t mac[MAC_ADDRESS_LENGTH];
     esp_wifi_get_mac(ESP_IF_WIFI_STA, mac);
     sprintf(cpy_default_hostname, "cpy_%s_%x", CIRCUITPY_BOARD_ID, (unsigned int)mac);
     const char *default_lwip_local_hostname = cpy_default_hostname;