IVPN server data update code and ISP filter (#578)

- Use IVPN's HTTP API instead of their .zip file
- Unit tests for API and GetServers
- Paves the way for Wireguard
- Update server information for IVPN
- Add `ISP` filter for IVPN

internal/updater/providers/ivpn/servers.go

@@ -6,78 +6,64 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"strings"
+	"net/http"
 
 	"github.com/qdm12/gluetun/internal/models"
-	"github.com/qdm12/gluetun/internal/updater/openvpn"
 	"github.com/qdm12/gluetun/internal/updater/resolver"
-	"github.com/qdm12/gluetun/internal/updater/unzip"
 )
 
-var ErrNotEnoughServers = errors.New("not enough servers found")
+var (
+	ErrFetchAPI         = errors.New("failed fetching API")
+	ErrNotEnoughServers = errors.New("not enough servers found")
+)
 
-func GetServers(ctx context.Context, unzipper unzip.Unzipper,
+func GetServers(ctx context.Context, client *http.Client,
 	presolver resolver.Parallel, minServers int) (
 	servers []models.IvpnServer, warnings []string, err error) {
-	const url = "https://www.ivpn.net/releases/config/ivpn-openvpn-config.zip"
-	contents, err := unzipper.FetchAndExtract(ctx, url)
+	data, err := fetchAPI(ctx, client)
 	if err != nil {
-		return nil, nil, err
-	} else if len(contents) < minServers {
+		return nil, nil, fmt.Errorf("%w: %s", ErrFetchAPI, err)
+	}
+
+	hosts := make([]string, 0, len(data.Servers))
+
+	for _, serverData := range data.Servers {
+		host := serverData.Hostnames.OpenVPN
+
+		if host == "" {
+			continue // Wireguard
+		}
+
+		hosts = append(hosts, host)
+	}
+
+	if len(hosts) < minServers {
 		return nil, nil, fmt.Errorf("%w: %d and expected at least %d",
-			ErrNotEnoughServers, len(contents), minServers)
+			ErrNotEnoughServers, len(hosts), minServers)
 	}
 
-	hts := make(hostToServer)
-
-	for fileName, content := range contents {
-		if !strings.HasSuffix(fileName, ".ovpn") {
-			continue // not an OpenVPN file
-		}
-
-		tcp, udp, err := openvpn.ExtractProto(content)
-		if err != nil {
-			// treat error as warning and go to next file
-			warning := err.Error() + ": in " + fileName
-			warnings = append(warnings, warning)
-			continue
-		}
-
-		host, warning, err := openvpn.ExtractHost(content)
-		if warning != "" {
-			warnings = append(warnings, warning)
-		}
-		if err != nil {
-			// treat error as warning and go to next file
-			warning := err.Error() + " in " + fileName
-			warnings = append(warnings, warning)
-			continue
-		}
-
-		country, city := parseFilename(fileName)
-
-		hts.add(host, country, city, tcp, udp)
-	}
-
-	if len(hts) < minServers {
-		return nil, warnings, fmt.Errorf("%w: %d and expected at least %d",
-			ErrNotEnoughServers, len(hts), minServers)
-	}
-
-	hosts := hts.toHostsSlice()
-	hostToIPs, newWarnings, err := resolveHosts(ctx, presolver, hosts, minServers)
-	warnings = append(warnings, newWarnings...)
+	hostToIPs, warnings, err := resolveHosts(ctx, presolver, hosts, minServers)
 	if err != nil {
 		return nil, warnings, err
 	}
 
-	hts.adaptWithIPs(hostToIPs)
+	servers = make([]models.IvpnServer, 0, len(hosts))
+	for _, serverData := range data.Servers {
+		host := serverData.Hostnames.OpenVPN
+		if serverData.Hostnames.OpenVPN == "" {
+			continue // Wireguard
+		}
 
-	servers = hts.toServersSlice()
-
-	if len(servers) < minServers {
-		return nil, warnings, fmt.Errorf("%w: %d and expected at least %d",
-			ErrNotEnoughServers, len(servers), minServers)
+		server := models.IvpnServer{
+			Country:  serverData.Country,
+			City:     serverData.City,
+			ISP:      serverData.ISP,
+			Hostname: serverData.Hostnames.OpenVPN,
+			// TCP is not supported
+			UDP: true,
+			IPs: hostToIPs[host],
+		}
+		servers = append(servers, server)
 	}
 
 	sortServers(servers)