Mullvad updater (#228)

* Add Mullvad to updater cli
* Update hardcoded servers for Mullvad

internal/models/server.go

@@ -1,36 +1,35 @@
 package models
 
 import (
+	"encoding/hex"
 	"fmt"
 	"net"
 	"strings"
 )
 
-func stringifyIPs(ips []net.IP) string {
-	ipStrings := make([]string, len(ips))
-	for i := range ips {
-		ipStrings[i] = fmt.Sprintf("{%s}", strings.ReplaceAll(ips[i].String(), ".", ", "))
-	}
-	return strings.Join(ipStrings, ", ")
-}
-
 type PIAServer struct {
 	IPs    []net.IP `json:"ips"`
 	Region string   `json:"region"`
 }
 
 func (p *PIAServer) String() string {
-	return fmt.Sprintf("{Region: %q, IPs: []net.IP{%s}}", p.Region, stringifyIPs(p.IPs))
+	return fmt.Sprintf("{Region: %q, IPs: %s}", p.Region, goStringifyIPs(p.IPs))
 }
 
 type MullvadServer struct {
 	IPs     []net.IP `json:"ips"`
+	IPsV6   []net.IP `json:"ipsv6"`
 	Country string   `json:"country"`
 	City    string   `json:"city"`
 	ISP     string   `json:"isp"`
 	Owned   bool     `json:"owned"`
 }
 
+func (s *MullvadServer) String() string {
+	return fmt.Sprintf("{Country: %q, City: %q, ISP: %q, Owned: %t, IPs: %s, IPsV6: %s}",
+		s.Country, s.City, s.ISP, s.Owned, goStringifyIPs(s.IPs), goStringifyIPs(s.IPsV6))
+}
+
 type WindscribeServer struct {
 	Region string   `json:"region"`
 	IPs    []net.IP `json:"ips"`
@@ -66,3 +65,49 @@ type PurevpnServer struct {
 	City    string   `json:"city"`
 	IPs     []net.IP `json:"ips"`
 }
+
+func goStringifyIP(ip net.IP) string {
+	s := fmt.Sprintf("%#v", ip)
+	s = strings.TrimSuffix(strings.TrimPrefix(s, "net.IP{"), "}")
+	fields := strings.Split(s, ", ")
+	isIPv4 := ip.To4() != nil
+	if isIPv4 {
+		fields = fields[len(fields)-4:]
+	}
+
+	// Count leading zeros
+	leadingZeros := 0
+	for i := range fields {
+		if fields[i] == "0x0" {
+			leadingZeros++
+		} else {
+			break
+		}
+	}
+
+	// Remove leading zeros
+	fields = fields[leadingZeros:]
+
+	for i := range fields {
+		// IPv4 is better understood in integer notation, whereas IPv6 is written in hex notation
+		if isIPv4 {
+			hexString := strings.Replace(fields[i], "0x", "", 1)
+			if len(hexString) == 1 {
+				hexString = "0" + hexString
+			}
+			b, _ := hex.DecodeString(hexString)
+			fields[i] = fmt.Sprintf("%d", b[0])
+		}
+	}
+
+	return fmt.Sprintf("net.IP{%s}", strings.Join(fields, ", "))
+}
+
+func goStringifyIPs(ips []net.IP) string {
+	ipStrings := make([]string, len(ips))
+	for i := range ips {
+		ipStrings[i] = goStringifyIP(ips[i])
+		ipStrings[i] = strings.TrimPrefix(ipStrings[i], "net.IP")
+	}
+	return "[]net.IP{" + strings.Join(ipStrings, ", ") + "}"
+}