chore(internal/providers): simplify OpenVPN config building

internal/provider/nordvpn/openvpnconf.go

@@ -1,8 +1,6 @@
 package nordvpn
 
 import (
-	"strconv"
-
 	"github.com/qdm12/gluetun/internal/configuration/settings"
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/models"
@@ -10,75 +8,29 @@ import (
 )
 
 func (n *Nordvpn) BuildConf(connection models.Connection,
-	settings settings.OpenVPN) (lines []string, err error) {
-	if len(settings.Ciphers) == 0 {
-		settings.Ciphers = []string{constants.AES256cbc, constants.AES256gcm}
+	settings settings.OpenVPN) (lines []string) {
+	//nolint:gomnd
+	providerSettings := utils.OpenVPNProviderSettings{
+		AuthUserPass: true,
+		Ciphers: []string{
+			constants.AES256cbc,
+			constants.AES256gcm,
+		},
+		Auth:          constants.SHA512,
+		Ping:          15,
+		RemoteCertTLS: true,
+		MssFix:        1450,
+		CA:            constants.NordvpnCA,
+		TLSAuth:       constants.NordvpnTLSAuth,
+		TunMTUExtra:   32,
+		RenegDisabled: true,
+		KeyDirection:  "1",
+		UDPLines: []string{
+			"fast-io",
+		},
+		ExtraLines: []string{
+			"comp-lzo no", // Explicitly disable compression
+		},
 	}
-
-	auth := *settings.Auth
-	if auth == "" {
-		auth = constants.SHA512
-	}
-
-	mssFix := *settings.MSSFix
-	if mssFix == 0 {
-		mssFix = 1450
-	}
-
-	lines = []string{
-		"client",
-		"nobind",
-		"tls-exit",
-		"dev " + settings.Interface,
-		"verb " + strconv.Itoa(*settings.Verbosity),
-
-		// Nordvpn specific
-		"tun-mtu-extra 32",
-		"mssfix " + strconv.Itoa(int(mssFix)),
-		"ping 15",
-		"remote-cert-tls server",
-		"reneg-sec 0",
-		"key-direction 1",
-		"auth-user-pass " + constants.OpenVPNAuthConf,
-		"auth " + auth,
-		"comp-lzo no", // Explicitly disable compression
-
-		// Added constant values
-		"auth-nocache",
-		"mute-replay-warnings",
-		"pull-filter ignore \"auth-token\"", // prevent auth failed loops
-		"auth-retry nointeract",
-		"suppress-timestamps",
-
-		// Connection variables
-		connection.OpenVPNProtoLine(),
-		connection.OpenVPNRemoteLine(),
-	}
-
-	lines = append(lines, utils.CipherLines(settings.Ciphers, settings.Version)...)
-
-	if connection.Protocol == constants.UDP {
-		lines = append(lines, "fast-io")
-		lines = append(lines, "explicit-exit-notify")
-	}
-
-	if settings.ProcessUser != "root" {
-		lines = append(lines, "user "+settings.ProcessUser)
-		lines = append(lines, "persist-tun")
-		lines = append(lines, "persist-key")
-	}
-
-	if !*settings.IPv6 {
-		lines = append(lines, `pull-filter ignore "route-ipv6"`)
-		lines = append(lines, `pull-filter ignore "ifconfig-ipv6"`)
-	}
-
-	lines = append(lines, utils.WrapOpenvpnCA(
-		constants.NordvpnCA)...)
-	lines = append(lines, utils.WrapOpenvpnTLSAuth(
-		constants.NordvpnTLSAuth)...)
-
-	lines = append(lines, "")
-
-	return lines, nil
+	return utils.OpenVPNConfig(providerSettings, connection, settings)
 }