Maintenance: refactor servers updater code

- Require at least 80% of number of servers now to pass
- Each provider is in its own package with a common structure
- Unzip package with unzipper interface
- Openvpn package with extraction and download functions

internal/updater/providers/nordvpn/api.go

@@ -0,0 +1,55 @@
+package nordvpn
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+)
+
+var (
+	ErrHTTPStatusCodeNotOK   = errors.New("HTTP status code not OK")
+	ErrUnmarshalResponseBody = errors.New("failed unmarshaling response body")
+)
+
+type serverData struct {
+	Domain    string `json:"domain"`
+	IPAddress string `json:"ip_address"`
+	Name      string `json:"name"`
+	Country   string `json:"country"`
+	Features  struct {
+		UDP bool `json:"openvpn_udp"`
+		TCP bool `json:"openvpn_tcp"`
+	} `json:"features"`
+}
+
+func fetchAPI(ctx context.Context, client *http.Client) (data []serverData, err error) {
+	const url = "https://nordvpn.com/api/server"
+
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	response, err := client.Do(request)
+	if err != nil {
+		return nil, err
+	}
+	defer response.Body.Close()
+
+	if response.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("%w: %s", ErrHTTPStatusCodeNotOK, response.Status)
+	}
+
+	decoder := json.NewDecoder(response.Body)
+	if err := decoder.Decode(&data); err != nil {
+		return nil, fmt.Errorf("%w: %s", ErrUnmarshalResponseBody, err)
+	}
+
+	if err := response.Body.Close(); err != nil {
+		return nil, err
+	}
+
+	return data, nil
+}

internal/updater/providers/nordvpn/ip.go

@@ -0,0 +1,16 @@
+package nordvpn
+
+import (
+	"fmt"
+	"net"
+)
+
+func parseIPv4(s string) (ipv4 net.IP, err error) {
+	ip := net.ParseIP(s)
+	if ip == nil {
+		return nil, fmt.Errorf("%w: %q", ErrParseIP, s)
+	} else if ip.To4() == nil {
+		return nil, fmt.Errorf("%w: %s", ErrNotIPv4, ip)
+	}
+	return ip, nil
+}

internal/updater/providers/nordvpn/name.go

@@ -0,0 +1,29 @@
+package nordvpn
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+var (
+	ErrNoIDInServerName      = errors.New("no ID in server name")
+	ErrInvalidIDInServerName = errors.New("invalid ID in server name")
+)
+
+func parseServerName(serverName string) (number uint16, err error) {
+	i := strings.IndexRune(serverName, '#')
+	if i < 0 {
+		return 0, fmt.Errorf("%w: %s", ErrNoIDInServerName, serverName)
+	}
+
+	idString := serverName[i+1:]
+	idUint64, err := strconv.ParseUint(idString, 10, 16)
+	if err != nil {
+		return 0, fmt.Errorf("%w: %s", ErrInvalidIDInServerName, serverName)
+	}
+
+	number = uint16(idUint64)
+	return number, nil
+}

internal/updater/providers/nordvpn/servers.go

@@ -0,0 +1,64 @@
+// Package nordvpn contains code to obtain the server information
+// for the NordVPN provider.
+package nordvpn
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+var (
+	ErrParseIP          = errors.New("cannot parse IP address")
+	ErrNotIPv4          = errors.New("IP address is not IPv4")
+	ErrNotEnoughServers = errors.New("not enough servers found")
+)
+
+func GetServers(ctx context.Context, client *http.Client, minServers int) (
+	servers []models.NordvpnServer, warnings []string, err error) {
+	data, err := fetchAPI(ctx, client)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	servers = make([]models.NordvpnServer, 0, len(data))
+
+	for _, jsonServer := range data {
+		if !jsonServer.Features.TCP && !jsonServer.Features.UDP {
+			warning := "server does not support TCP and UDP for openvpn: " + jsonServer.Name
+			warnings = append(warnings, warning)
+			continue
+		}
+
+		ip, err := parseIPv4(jsonServer.IPAddress)
+		if err != nil {
+			return nil, nil, fmt.Errorf("%w for server %s", err, jsonServer.Name)
+		}
+
+		number, err := parseServerName(jsonServer.Name)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		server := models.NordvpnServer{
+			Region: jsonServer.Country,
+			Number: number,
+			IP:     ip,
+			TCP:    jsonServer.Features.TCP,
+			UDP:    jsonServer.Features.UDP,
+		}
+		servers = append(servers, server)
+	}
+
+	if len(servers) < minServers {
+		return nil, warnings, fmt.Errorf("%w: %d and expected at least %d",
+			ErrNotEnoughServers, len(servers), minServers)
+	}
+
+	sortServers(servers)
+
+	return servers, warnings, nil
+}

internal/updater/providers/nordvpn/sort.go

@@ -0,0 +1,16 @@
+package nordvpn
+
+import (
+	"sort"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func sortServers(servers []models.NordvpnServer) {
+	sort.Slice(servers, func(i, j int) bool {
+		if servers[i].Region == servers[j].Region {
+			return servers[i].Number < servers[j].Number
+		}
+		return servers[i].Region < servers[j].Region
+	})
+}

internal/updater/providers/nordvpn/string.go

@@ -0,0 +1,14 @@
+package nordvpn
+
+import "github.com/qdm12/gluetun/internal/models"
+
+func Stringify(servers []models.NordvpnServer) (s string) {
+	s = "func NordvpnServers() []models.NordvpnServer {\n"
+	s += "	return []models.NordvpnServer{\n"
+	for _, server := range servers {
+		s += "		" + server.String() + ",\n"
+	}
+	s += "	}\n"
+	s += "}"
+	return s
+}