Add a function to auto lookup our timezone using our public ip

src/utilities.cpp

@@ -6,6 +6,7 @@
 #include "LittleFS.h"
 #include "comms.h"
 #include <ESP8266WiFi.h>
+#include <ESP8266HTTPClient.h>
 
 #ifdef LEGACY_SETTINGS_MIGRATION
 // Filenames for legacy user configuation, replaced by single file.
@@ -51,6 +52,38 @@ bool enableNTP = false;
 unsigned long lastRebootAt = 0;
 int32_t savedDoorUpdateAt = 0;
 
+int get_tz()
+{
+    WiFiClient client;
+    HTTPClient http;
+
+    if (http.begin(client, "http://ip-api.com/csv/?fields=timezone,offset"))
+    { // HTTP
+
+        // start connection and send HTTP header
+        int httpCode = http.GET();
+
+        // httpCode will be negative on error
+        if (httpCode > 0)
+        {
+            if (httpCode == HTTP_CODE_OK || httpCode == HTTP_CODE_MOVED_PERMANENTLY)
+            {
+                String payload = http.getString();
+                char * timezone = (char*)payload.c_str();
+                char * ch = strchr(timezone, ',');
+                *ch = '\0';
+                ch++;
+                int offset = atoi(ch);
+                offset /= 3600;
+                RINFO("Setting timezone to %s, %d", timezone, offset);
+                return offset;
+            }
+        }
+        http.end();
+    }
+    return 0;
+}
+
 void time_is_set(bool from_sntp)
 {
     RINFO("Clock set from NTP server: %d", from_sntp ? 1 : 0);