Update your IPv4 + IPv6 addresses only when they change. With several domains support.

netlibre golang update script

package main

import (
	b64 "encoding/base64"
	"io/ioutil"
	"net"
	"net/http"
	"strings"
)

var nddservice = "netlib.re"
var domains = map[string]string{"netlib.re": "testsubdomain", "codelib.re": "testsubdomain"}
var login = "testlogin"
var pass = b64.StdEncoding.EncodeToString([]byte("testpwd"))

func getIPv6() string {
	conn, err := net.Dial("tcp6", "google.com:http")
	defer conn.Close()
	if err != nil {
		return ""
	}
	localAddr := conn.LocalAddr().String()
	idx := strings.LastIndex(localAddr, ":")
	return localAddr[1 : idx-1]
}

func getIPv4() string {
	client := &http.Client{}
	client.Transport = &http.Transport{
		Dial: (func(network, addr string) (net.Conn, error) {
			return (&net.Dialer{
				Timeout: 3 * time.Second,
			}).Dial("tcp4", addr)
		}),
	}
	resp, err := client.Get("http://t.karchnu.fr/ip.php")
	if err == nil {
		contents, err := ioutil.ReadAll(resp.Body)
		if err == nil {
			defer resp.Body.Close()
			return strings.TrimSpace(string(contents))
		}
	}
	return ""
}

func filterIps(domain string, ip4, ip6 *string) {
	ips, err := net.LookupIP(domain)
	if err == nil {
		for _, ip := range ips {
			ipaddr := ip.String()
			if ipaddr == *ip4 {
				*ip4 = ""
			}
			if ipaddr == *ip6 {
				*ip6 = ""
			}
		}
	}
}

func main() {
	ipv4 := getIPv4()
	ipv6 := getIPv6()
	if len(ipv4) == 0 && len(ipv6) == 0 {
		return
	}
	for service, subdomain := range domains {
		ip4 := string(ipv4)
		ip6 := string(ipv6)
		domain := subdomain + "." + service
		filterIps(domain, &ip4, &ip6)

		baseURL := "https://" + nddservice + "/domain/cliup/" + login + "/" + pass + "/" + domain + "/@"
		if len(ip4) > 0 {
			resp, err := http.Get(baseURL + "/A/" + ip4)
			if err != nil {
				defer resp.Body.Close()
			}
		}
		if len(ip6) > 0 {
			resp, err := http.Get(baseURL + "/AAAA/" + ip6)
			if err != nil {
				defer resp.Body.Close()
			}
		}
	}
}