PIA nextgen portforward (#242)

* Split provider/pia.go in piav3.go and piav4.go
* Change port forwarding signature
* Enable port forwarding parameter for PIA v4
* Fix VPN gateway IP obtention
* Setup HTTP client for TLS with custom cert
* Error message for regions not supporting pf

internal/provider/piav3.go

@@ -0,0 +1,94 @@
+package provider
+
+import (
+	"context"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"net/http"
+
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/firewall"
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/qdm12/golibs/crypto/random"
+	"github.com/qdm12/golibs/files"
+	"github.com/qdm12/golibs/logging"
+)
+
+type piaV3 struct {
+	random  random.Random
+	servers []models.PIAServer
+}
+
+func newPrivateInternetAccessV3(servers []models.PIAServer) *piaV3 {
+	return &piaV3{
+		random:  random.NewRandom(),
+		servers: servers,
+	}
+}
+
+func (p *piaV3) GetOpenVPNConnections(selection models.ServerSelection) (connections []models.OpenVPNConnection, err error) {
+	return getPIAOpenVPNConnections(p.servers, selection)
+}
+
+func (p *piaV3) BuildConf(connections []models.OpenVPNConnection, verbosity, uid, gid int, root bool, cipher, auth string, extras models.ExtraConfigOptions) (lines []string) {
+	return buildPIAConf(connections, verbosity, root, cipher, auth, extras)
+}
+
+func (p *piaV3) PortForward(ctx context.Context, client *http.Client,
+	fileManager files.FileManager, pfLogger logging.Logger, gateway net.IP, fw firewall.Configurator,
+	syncState func(port uint16) (pfFilepath models.Filepath)) {
+	b, err := p.random.GenerateRandomBytes(32)
+	if err != nil {
+		pfLogger.Error(err)
+		return
+	}
+	clientID := hex.EncodeToString(b)
+	url := fmt.Sprintf("%s/?client_id=%s", constants.PIAPortForwardURL, clientID)
+	response, err := client.Get(url) // TODO add ctx
+	if err != nil {
+		pfLogger.Error(err)
+		return
+	}
+	defer response.Body.Close()
+	if response.StatusCode != http.StatusOK {
+		pfLogger.Error(fmt.Errorf("%s for %s; does your PIA server support port forwarding?", response.Status, url))
+		return
+	}
+	b, err = ioutil.ReadAll(response.Body)
+	if err != nil {
+		pfLogger.Error(err)
+		return
+	} else if len(b) == 0 {
+		pfLogger.Error(fmt.Errorf("port forwarding is already activated on this connection, has expired, or you are not connected to a PIA region that supports port forwarding"))
+		return
+	}
+	body := struct {
+		Port uint16 `json:"port"`
+	}{}
+	if err := json.Unmarshal(b, &body); err != nil {
+		pfLogger.Error(fmt.Errorf("port forwarding response: %w", err))
+		return
+	}
+	port := body.Port
+
+	filepath := syncState(port)
+	pfLogger.Info("Writing port to %s", filepath)
+	if err := fileManager.WriteToFile(
+		string(filepath), []byte(fmt.Sprintf("%d", port)),
+		files.Permissions(0666),
+	); err != nil {
+		pfLogger.Error(err)
+	}
+
+	if err := fw.SetAllowedPort(ctx, port, string(constants.TUN)); err != nil {
+		pfLogger.Error(err)
+	}
+
+	<-ctx.Done()
+	if err := fw.RemoveAllowedPort(ctx, port); err != nil {
+		pfLogger.Error(err)
+	}
+}