WiFi - static IP auto gw,mask,dns as in Arduino libraries

libraries/ESP8266WiFi/src/ESP8266WiFiSTA.cpp

@@ -339,6 +339,22 @@ bool ESP8266WiFiSTAClass::config(IPAddress local_ip, IPAddress arg1, IPAddress a
   return true;
 }
 
+bool ESP8266WiFiSTAClass::config(IPAddress local_ip, IPAddress dns) {
+
+    if (!local_ip.isSet())
+        return config(INADDR_ANY, INADDR_ANY, INADDR_ANY);
+
+    if (!local_ip.isV4())
+        return false;
+
+    IPAddress gw(local_ip);
+    gw[3] = 1;
+    if (!dns.isSet()) {
+        dns = gw;
+    }
+    return config(local_ip, dns, gw);
+}
+
 /**
  * Change DNS for static IP configuration
  * @param dns1       Static DNS server 1

libraries/ESP8266WiFi/src/ESP8266WiFiSTA.h

@@ -46,6 +46,11 @@ class ESP8266WiFiSTAClass: public LwipIntf {
         //to detect Arduino arg order, and handle it correctly. Be aware that the Arduino default value handling doesn't
         //work here (see Arduino docs for gway/subnet defaults). In other words: at least 3 args must always be given.
         bool config(IPAddress local_ip, IPAddress gateway, IPAddress subnet, IPAddress dns1 = INADDR_ANY, IPAddress dns2 = INADDR_ANY);
+
+        // two and one parameter version. 2nd parameter is DNS like in Arduino
+        // IPv4 only
+        bool config(IPAddress local_ip, IPAddress dns = INADDR_ANY);
+
         bool setDNS(IPAddress dns1, IPAddress dns2 = INADDR_ANY);
 
         bool reconnect();