feat(privatevpn): native port forwarding support (#2285)

internal/provider/privatevpn/portforward.go

@@ -0,0 +1,81 @@
+package privatevpn
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"strconv"
+
+	"github.com/qdm12/gluetun/internal/provider/common"
+	"github.com/qdm12/gluetun/internal/provider/utils"
+)
+
+var (
+	regexPort = regexp.MustCompile(`[1-9][0-9]{0,4}`)
+)
+
+var (
+	ErrPortForwardedNotFound = errors.New("port forwarded not found")
+)
+
+// PortForward obtains a VPN server side port forwarded from the PrivateVPN API.
+// It returns 0 if all ports are to forwarded on a dedicated server IP.
+func (p *Provider) PortForward(ctx context.Context, objects utils.PortForwardObjects) (
+	ports []uint16, err error) {
+	url := "https://connect.pvdatanet.com/v3/Api/port?ip[]=" + objects.InternalIP.String()
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("creating HTTP request: %w", err)
+	}
+
+	response, err := objects.Client.Do(request)
+	if err != nil {
+		return nil, fmt.Errorf("sending HTTP request: %w", err)
+	}
+
+	if response.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("%w: %d %s", common.ErrHTTPStatusCodeNotOK,
+			response.StatusCode, response.Status)
+	}
+
+	defer response.Body.Close()
+
+	bytes, err := io.ReadAll(response.Body)
+	if err != nil {
+		return nil, fmt.Errorf("reading response body: %w", err)
+	}
+
+	var data struct {
+		Status    string `json:"status"`
+		Supported bool   `json:"supported"`
+	}
+	err = json.Unmarshal(bytes, &data)
+	if err != nil {
+		return nil, fmt.Errorf("decoding JSON response: %w; data is: %s",
+			err, string(bytes))
+	} else if !data.Supported {
+		return nil, fmt.Errorf("%w for this VPN server", common.ErrPortForwardNotSupported)
+	}
+
+	portString := regexPort.FindString(data.Status)
+	if portString == "" {
+		return nil, fmt.Errorf("%w: in status %q", ErrPortForwardedNotFound, data.Status)
+	}
+
+	const base, bitSize = 10, 16
+	portUint64, err := strconv.ParseUint(portString, base, bitSize)
+	if err != nil {
+		return nil, fmt.Errorf("parsing port: %w", err)
+	}
+	return []uint16{uint16(portUint64)}, nil
+}
+
+func (p *Provider) KeepPortForward(ctx context.Context,
+	_ utils.PortForwardObjects) (err error) {
+	<-ctx.Done()
+	return ctx.Err()
+}