Fix #170

internal/publicip/publicip.go

@@ -0,0 +1,53 @@
+package publicip
+
+import (
+	"fmt"
+	"math/rand"
+	"net"
+	"net/http"
+	"strings"
+
+	"github.com/qdm12/golibs/network"
+)
+
+type IPGetter interface {
+	Get() (ip net.IP, err error)
+}
+
+type ipGetter struct {
+	client   network.Client
+	randIntn func(n int) int
+}
+
+func NewIPGetter(client network.Client) IPGetter {
+	return &ipGetter{
+		client:   client,
+		randIntn: rand.Intn,
+	}
+}
+
+func (i *ipGetter) Get() (ip net.IP, err error) {
+	urls := []string{
+		"http://ip1.dynupdate.no-ip.com:8245",
+		"http://ip1.dynupdate.no-ip.com",
+		"https://api.ipify.org",
+		"https://diagnostic.opendns.com/myip",
+		"https://domains.google.com/checkip",
+		"https://ifconfig.io/ip",
+		"https://ip4.ddnss.de/meineip.php",
+		"https://ipinfo.io/ip",
+	}
+	url := urls[i.randIntn(len(urls))]
+	content, status, err := i.client.GetContent(url, network.UseRandomUserAgent())
+	if err != nil {
+		return nil, err
+	} else if status != http.StatusOK {
+		return nil, fmt.Errorf("received unexpected status code %d from %s", status, url)
+	}
+	s := strings.ReplaceAll(string(content), "\n", "")
+	ip = net.ParseIP(s)
+	if ip == nil {
+		return nil, fmt.Errorf("cannot parse IP address from %q", s)
+	}
+	return ip, nil
+}