Mullvad updater (#228)

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

internal/updater/mullvad.go

@@ -0,0 +1,87 @@
+package updater
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"sort"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func (u *updater) findMullvadServers() (servers []models.MullvadServer, err error) {
+	const url = "https://api.mullvad.net/www/relays/openvpn/"
+	response, err := u.httpGet(url)
+	if err != nil {
+		return nil, err
+	}
+	defer response.Body.Close()
+	if response.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf(response.Status)
+	}
+	bytes, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return nil, err
+	}
+	var data []struct {
+		Country  string `json:"country_name"`
+		City     string `json:"city_name"`
+		Active   bool   `json:"active"`
+		Owned    bool   `json:"owned"`
+		Provider string `json:"provider"`
+		IPv4     string `json:"ipv4_addr_in"`
+		IPv6     string `json:"ipv6_addr_in"`
+	}
+	if err := json.Unmarshal(bytes, &data); err != nil {
+		return nil, err
+	}
+	serversByKey := map[string]models.MullvadServer{}
+	for _, jsonServer := range data {
+		if !jsonServer.Active {
+			continue
+		}
+		ipv4 := net.ParseIP(jsonServer.IPv4)
+		ipv6 := net.ParseIP(jsonServer.IPv6)
+		if ipv4 == nil || ipv4.To4() == nil {
+			return nil, fmt.Errorf("cannot parse ipv4 address %q", jsonServer.IPv4)
+		} else if ipv6 == nil || ipv6.To4() != nil {
+			return nil, fmt.Errorf("cannot parse ipv6 address %q", jsonServer.IPv6)
+		}
+		key := fmt.Sprintf("%s%s%t%s", jsonServer.Country, jsonServer.City, jsonServer.Owned, jsonServer.Provider)
+		if server, ok := serversByKey[key]; ok {
+			server.IPs = append(server.IPs, ipv4)
+			server.IPsV6 = append(server.IPsV6, ipv6)
+			serversByKey[key] = server
+		} else {
+			serversByKey[key] = models.MullvadServer{
+				IPs:     []net.IP{ipv4},
+				IPsV6:   []net.IP{ipv6},
+				Country: jsonServer.Country,
+				City:    jsonServer.City,
+				ISP:     jsonServer.Provider,
+				Owned:   jsonServer.Owned,
+			}
+		}
+	}
+	for _, server := range serversByKey {
+		servers = append(servers, server)
+	}
+	sort.Slice(servers, func(i, j int) bool {
+		return servers[i].Country+servers[i].City+servers[i].ISP < servers[j].Country+servers[j].City+servers[j].ISP
+	})
+	return servers, nil
+}
+
+//nolint:goconst
+func stringifyMullvadServers(servers []models.MullvadServer) (s string) {
+	s = "func MullvadServers() []models.MullvadServer {\n"
+	s += "	return []models.MullvadServer{\n"
+	for _, server := range servers {
+		s += "		" + server.String() + ",\n"
+	}
+	s += "	}\n"
+	s += "}"
+	return s
+}