LwipIntfDev - added macAddress getter and DNS IP getter and setter (#1856)

and dnsIP(n) getter in WiFiClass too

libraries/WiFi/src/WiFiClass.cpp

@@ -326,6 +326,15 @@ IPAddress WiFiClass::gatewayIP() {
     return _wifi.gatewayIP();
 }
 
+/*
+    Get the DNS ip address.
+
+    return: IPAddress DNS Server IP
+*/
+IPAddress WiFiClass::dnsIP(uint8_t dns_no) {
+    return _wifi.dnsIP(dns_no);
+}
+
 /*
     Return the current SSID associated with the network
 

libraries/WiFi/src/WiFiClass.h

@@ -261,6 +261,13 @@ public:
     */
     IPAddress gatewayIP();
 
+    /*
+        Get the DNS ip address.
+
+        return: IPAddress DNS Server IP
+    */
+    IPAddress dnsIP(uint8_t dns_no = 0);
+
     /*
         Return the current SSID associated with the network
 

libraries/lwIP_Ethernet/src/LwipIntfDev.h

@@ -73,6 +73,10 @@ public:
         return &_netif;
     }
 
+    uint8_t* macAddress(uint8_t* mac) {
+        memcpy(mac, &_netif.hwaddr, 6);
+        return mac;
+    }
     IPAddress localIP() const {
         return IPAddress(ip4_addr_get_u32(ip_2_ip4(&_netif.ip_addr)));
     }
@@ -82,6 +86,17 @@ public:
     IPAddress gatewayIP() const {
         return IPAddress(ip4_addr_get_u32(ip_2_ip4(&_netif.gw)));
     }
+    IPAddress dnsIP(int n = 0) const {
+        return IPAddress(dns_getserver(n));
+    }
+    void setDNS(IPAddress dns1, IPAddress dns2 = INADDR_ANY) {
+        if (dns1.isSet()) {
+            dns_setserver(0, dns1);
+        }
+        if (dns2.isSet()) {
+            dns_setserver(1, dns2);
+        }
+    }
 
     // 1. Currently when no default is set, esp8266-Arduino uses the first
     //    DHCP client interface receiving a valid address and gateway to