dummy build on windows; move code

dhcpd/helpers.go

@@ -39,6 +39,26 @@ func parseIPv4(text string) (net.IP, error) {
 	return result.To4(), nil
 }
 
+// Get IPv4 address list
+func getIfaceIPv4(iface net.Interface) []net.IP {
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return nil
+	}
+
+	var res []net.IP
+	for _, a := range addrs {
+		ipnet, ok := a.(*net.IPNet)
+		if !ok {
+			continue
+		}
+		if ipnet.IP.To4() != nil {
+			res = append(res, ipnet.IP.To4())
+		}
+	}
+	return res
+}
+
 // Return TRUE if subnet mask is correct (e.g. 255.255.255.0)
 func isValidSubnetMask(mask net.IP) bool {
 	var n uint32