chore(internal/providers): simplify OpenVPN config building

internal/provider/expressvpn/openvpnconf.go

@@ -1,8 +1,6 @@
 package expressvpn
 
 import (
-	"strconv"
-
 	"github.com/qdm12/gluetun/internal/configuration/settings"
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/models"
@@ -10,79 +8,28 @@ import (
 )
 
 func (p *Provider) BuildConf(connection models.Connection,
-	settings settings.OpenVPN) (lines []string, err error) {
-	if len(settings.Ciphers) == 0 {
-		settings.Ciphers = []string{constants.AES256cbc}
+	settings settings.OpenVPN) (lines []string) {
+	//nolint:gomnd
+	providerSettings := utils.OpenVPNProviderSettings{
+		RemoteCertTLS: true,
+		AuthUserPass:  true,
+		Ciphers: []string{
+			constants.AES256cbc,
+		},
+		Auth:           constants.SHA512,
+		CA:             constants.ExpressvpnCA,
+		Cert:           constants.ExpressvpnCert,
+		RSAKey:         constants.ExpressvpnRSAKey,
+		TLSAuth:        constants.ExpressvpnTLSAuth,
+		MssFix:         1200,
+		FastIO:         true,
+		Fragment:       1300,
+		SndBuf:         524288,
+		RcvBuf:         524288,
+		KeyDirection:   "1",
+		VerifyX509Type: "name-prefix",
+		// Always verify against `Server` x509 name prefix, security hole I guess?
+		VerifyX509Name: "Server",
 	}
-	auth := *settings.Auth
-	if auth == "" {
-		auth = constants.SHA512
-	}
-
-	mssFix := *settings.MSSFix
-	if mssFix == 0 {
-		const defaultMSSFix = 1200
-		mssFix = defaultMSSFix
-	}
-
-	lines = []string{
-		"client",
-		"nobind",
-		"tls-exit",
-		"dev " + settings.Interface,
-		"verb " + strconv.Itoa(*settings.Verbosity),
-
-		// Expressvpn specific
-		"fast-io",
-		"fragment 1300",
-		"mssfix " + strconv.Itoa(int(mssFix)),
-		"sndbuf 524288",
-		"rcvbuf 524288",
-		"verify-x509-name Server name-prefix", // security hole I guess?
-		"remote-cert-tls server",              // updated name of ns-cert-type
-		"key-direction 1",
-		"auth-user-pass " + constants.OpenVPNAuthConf,
-		"auth " + auth,
-
-		// Added constant values
-		"mute-replay-warnings",
-		"auth-nocache",
-		"pull-filter ignore \"auth-token\"", // prevent auth failed loops
-		"auth-retry nointeract",
-		"suppress-timestamps",
-
-		// Modified variables
-		connection.OpenVPNProtoLine(),
-		connection.OpenVPNRemoteLine(),
-	}
-
-	lines = append(lines, utils.CipherLines(settings.Ciphers, settings.Version)...)
-
-	if connection.Protocol == constants.UDP {
-		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.WrapOpenvpnCert(
-		constants.ExpressvpnCert)...)
-	lines = append(lines, utils.WrapOpenvpnRSAKey(
-		constants.ExpressvpnRSAKey)...)
-	lines = append(lines, utils.WrapOpenvpnTLSAuth(
-		constants.ExpressvpnTLSAuth)...)
-	lines = append(lines, utils.WrapOpenvpnCA(
-		constants.ExpressvpnCA)...)
-
-	lines = append(lines, "")
-
-	return lines, nil
+	return utils.OpenVPNConfig(providerSettings, connection, settings)
 }