hotfix(openvpn): fix support for tcp-client

- always use `proto tcp-client` when using TCP
- parses `tcp-client` (on top of `tcp`, `tcp4`, `tcp6`) as meaning TCP
- Fix #3302

internal/provider/utils/openvpn.go

@@ -65,7 +65,11 @@ func OpenVPNConfig(provider OpenVPNProviderSettings,
 	lines.add("handshake-window", "10")   // default is 60 seconds which is too long
 	lines.add("dev", settings.Interface)
 	lines.add("verb", fmt.Sprint(*settings.Verbosity))
-	lines.add("proto", connection.Protocol)
+	protocol := connection.Protocol
+	if protocol == constants.TCP {
+		protocol = "tcp-client"
+	}
+	lines.add("proto", protocol)
 	lines.add("remote", connection.IP.String(), fmt.Sprint(connection.Port))
 
 	if *settings.User != "" {

internal/updater/openvpn/extract.go

@@ -25,7 +25,7 @@ func ExtractProto(b []byte) (tcp, udp bool, err error) {
 		s = strings.TrimSpace(s)
 		s = strings.ToLower(s)
 		switch s {
-		case "tcp", "tcp4", "tcp6":
+		case "tcp", "tcp4", "tcp6", "tcp-client":
 			return true, false, nil
 		case "udp", "udp4", "udp6":
 			return false, true, nil