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/privado/hosttoserver.go

@@ -0,0 +1,53 @@
+package privado
+
+import (
+	"net"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+type hostToServer map[string]models.PrivadoServer
+
+func (hts hostToServer) add(host string) {
+	server, ok := hts[host]
+	if ok {
+		return
+	}
+	server.Hostname = host
+	hts[host] = server
+}
+
+func (hts hostToServer) toHostsSlice() (hosts []string) {
+	hosts = make([]string, 0, len(hts))
+	for host := range hts {
+		hosts = append(hosts, host)
+	}
+	return hosts
+}
+
+func (hts hostToServer) adaptWithIPs(hostToIPs map[string][]net.IP) (
+	warnings []string) {
+	for host, IPs := range hostToIPs {
+		if len(IPs) > 1 {
+			warning := "more than one IP address found for host " + host
+			warnings = append(warnings, warning)
+		}
+		server := hts[host]
+		server.IP = IPs[0]
+		hts[host] = server
+	}
+	for host, server := range hts {
+		if server.IP == nil {
+			delete(hts, host)
+		}
+	}
+	return warnings
+}
+
+func (hts hostToServer) toServersSlice() (servers []models.PrivadoServer) {
+	servers = make([]models.PrivadoServer, 0, len(hts))
+	for _, server := range hts {
+		servers = append(servers, server)
+	}
+	return servers
+}

internal/updater/providers/privado/resolve.go

@@ -0,0 +1,31 @@
+package privado
+
+import (
+	"context"
+	"net"
+	"time"
+
+	"github.com/qdm12/gluetun/internal/updater/resolver"
+)
+
+func resolveHosts(ctx context.Context, presolver resolver.Parallel,
+	hosts []string, minServers int) (hostToIPs map[string][]net.IP,
+	warnings []string, err error) {
+	const (
+		maxFailRatio = 0.1
+		maxDuration  = 3 * time.Second
+		maxNoNew     = 1
+		maxFails     = 2
+	)
+	settings := resolver.ParallelSettings{
+		MaxFailRatio: maxFailRatio,
+		MinFound:     minServers,
+		Repeat: resolver.RepeatSettings{
+			MaxDuration: maxDuration,
+			MaxNoNew:    maxNoNew,
+			MaxFails:    maxFails,
+			SortIPs:     true,
+		},
+	}
+	return presolver.Resolve(ctx, hosts, settings)
+}

internal/updater/providers/privado/servers.go

@@ -0,0 +1,72 @@
+// Package privado contains code to obtain the server information
+// for the Privado provider.
+package privado
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"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")
+
+func GetServers(ctx context.Context, unzipper unzip.Unzipper,
+	presolver resolver.Parallel, minServers int) (
+	servers []models.PrivadoServer, warnings []string, err error) {
+	const url = "https://privado.io/apps/ovpn_configs.zip"
+	contents, err := unzipper.FetchAndExtract(ctx, url)
+	if err != nil {
+		return nil, nil, err
+	} else if len(contents) < minServers {
+		return nil, nil, fmt.Errorf("%w: %d and expected at least %d",
+			ErrNotEnoughServers, len(contents), minServers)
+	}
+
+	hts := make(hostToServer)
+
+	for fileName, content := range contents {
+		if !strings.HasSuffix(fileName, ".ovpn") {
+			continue // not an OpenVPN file
+		}
+
+		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
+		}
+
+		hts.add(host)
+	}
+
+	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...)
+	if err != nil {
+		return nil, warnings, err
+	}
+
+	newWarnings = hts.adaptWithIPs(hostToIPs)
+	warnings = append(warnings, newWarnings...)
+
+	servers = hts.toServersSlice()
+
+	sortServers(servers)
+
+	return servers, warnings, nil
+}

internal/updater/providers/privado/sort.go

@@ -0,0 +1,13 @@
+package privado
+
+import (
+	"sort"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func sortServers(servers []models.PrivadoServer) {
+	sort.Slice(servers, func(i, j int) bool {
+		return servers[i].Hostname < servers[j].Hostname
+	})
+}

internal/updater/providers/privado/string.go

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