Maint: split custom config files in openvpn/custom

internal/openvpn/custom/custom.go

@@ -3,237 +3,29 @@ package custom
 import (
 	"errors"
 	"fmt"
-	"io"
-	"net"
-	"os"
-	"strconv"
-	"strings"
 
 	"github.com/qdm12/gluetun/internal/configuration"
-	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/models"
-	"github.com/qdm12/gluetun/internal/provider/utils"
 )
 
 var (
-	errReadCustomConfig  = errors.New("cannot read custom configuration file")
+	ErrReadCustomConfig  = errors.New("cannot read custom configuration file")
-	errExtractConnection = errors.New("cannot extract connection from custom configuration file")
+	ErrExtractConnection = errors.New("cannot extract connection from custom configuration file")
 )
 
-func ProcessCustomConfig(settings configuration.OpenVPN) (
+func BuildConfig(settings configuration.OpenVPN) (
 	lines []string, connection models.OpenVPNConnection, err error) {
 	lines, err = readCustomConfigLines(settings.Config)
 	if err != nil {
-		return nil, connection, fmt.Errorf("%w: %s", errReadCustomConfig, err)
+		return nil, connection, fmt.Errorf("%w: %s", ErrReadCustomConfig, err)
 	}
 
 	connection, err = extractConnectionFromLines(lines)
 	if err != nil {
-		return nil, connection, fmt.Errorf("%w: %s", errExtractConnection, err)
+		return nil, connection, fmt.Errorf("%w: %s", ErrExtractConnection, err)
 	}
 
 	lines = modifyCustomConfig(lines, settings, connection)
 
 	return lines, connection, nil
 }
-
-func readCustomConfigLines(filepath string) (
-	lines []string, err error) {
-	file, err := os.Open(filepath)
-	if err != nil {
-		return nil, err
-	}
-
-	b, err := io.ReadAll(file)
-	if err != nil {
-		_ = file.Close()
-		return nil, err
-	}
-
-	if err := file.Close(); err != nil {
-		return nil, err
-	}
-
-	return strings.Split(string(b), "\n"), nil
-}
-
-func modifyCustomConfig(lines []string, settings configuration.OpenVPN,
-	connection models.OpenVPNConnection) (modified []string) {
-	// Remove some lines
-	for _, line := range lines {
-		switch {
-		case strings.HasPrefix(line, "up "),
-			strings.HasPrefix(line, "down "),
-			strings.HasPrefix(line, "verb "),
-			strings.HasPrefix(line, "auth-user-pass "),
-			strings.HasPrefix(line, "user "),
-			strings.HasPrefix(line, "proto "),
-			strings.HasPrefix(line, "remote "),
-			settings.Cipher != "" && strings.HasPrefix(line, "cipher "),
-			settings.Cipher != "" && strings.HasPrefix(line, "data-ciphers "),
-			settings.Auth != "" && strings.HasPrefix(line, "auth "),
-			settings.MSSFix > 0 && strings.HasPrefix(line, "mssfix "),
-			!settings.IPv6 && strings.HasPrefix(line, "tun-ipv6"):
-		default:
-			modified = append(modified, line)
-		}
-	}
-
-	// Add values
-	modified = append(modified, connection.ProtoLine())
-	modified = append(modified, connection.RemoteLine())
-	modified = append(modified, "mute-replay-warnings")
-	modified = append(modified, "auth-nocache")
-	modified = append(modified, "pull-filter ignore \"auth-token\"") // prevent auth failed loop
-	modified = append(modified, "auth-retry nointeract")
-	modified = append(modified, "suppress-timestamps")
-	if settings.User != "" {
-		modified = append(modified, "auth-user-pass "+constants.OpenVPNAuthConf)
-	}
-	modified = append(modified, "verb "+strconv.Itoa(settings.Verbosity))
-	if settings.Cipher != "" {
-		modified = append(modified, utils.CipherLines(settings.Cipher, settings.Version)...)
-	}
-	if settings.Auth != "" {
-		modified = append(modified, "auth "+settings.Auth)
-	}
-	if settings.MSSFix > 0 {
-		modified = append(modified, "mssfix "+strconv.Itoa(int(settings.MSSFix)))
-	}
-	if !settings.IPv6 {
-		modified = append(modified, `pull-filter ignore "route-ipv6"`)
-		modified = append(modified, `pull-filter ignore "ifconfig-ipv6"`)
-	}
-	if !settings.Root {
-		modified = append(modified, "user "+settings.ProcUser)
-	}
-
-	return modified
-}
-
-var (
-	errRemoteLineNotFound = errors.New("remote line not found")
-)
-
-// extractConnectionFromLines always takes the first remote line only.
-func extractConnectionFromLines(lines []string) (
-	connection models.OpenVPNConnection, err error) {
-	for i, line := range lines {
-		newConnectionData, err := extractConnectionFromLine(line)
-		if err != nil {
-			return connection, fmt.Errorf("on line %d: %w", i+1, err)
-		}
-		connection.UpdateEmptyWith(newConnectionData)
-
-		if connection.Protocol != "" && connection.IP != nil {
-			break
-		}
-	}
-
-	if connection.IP == nil {
-		return connection, errRemoteLineNotFound
-	}
-
-	if connection.Protocol == "" {
-		connection.Protocol = constants.UDP
-	}
-
-	if connection.Port == 0 {
-		connection.Port = 1194
-		if connection.Protocol == constants.TCP {
-			connection.Port = 443
-		}
-	}
-
-	return connection, nil
-}
-
-var (
-	errExtractProto  = errors.New("failed extracting protocol from proto line")
-	errExtractRemote = errors.New("failed extracting protocol from remote line")
-)
-
-func extractConnectionFromLine(line string) (
-	connection models.OpenVPNConnection, err error) {
-	switch {
-	case strings.HasPrefix(line, "proto "):
-		connection.Protocol, err = extractProto(line)
-		if err != nil {
-			return connection, fmt.Errorf("%w: %s", errExtractProto, err)
-		}
-
-	// only take the first remote line
-	case strings.HasPrefix(line, "remote ") && connection.IP == nil:
-		connection.IP, connection.Port, connection.Protocol, err = extractRemote(line)
-		if err != nil {
-			return connection, fmt.Errorf("%w: %s", errExtractRemote, err)
-		}
-	}
-
-	return connection, nil
-}
-
-var (
-	errProtoLineFieldsCount = errors.New("proto line has not 2 fields as expected")
-	errProtocolNotSupported = errors.New("network protocol not supported")
-)
-
-func extractProto(line string) (protocol string, err error) {
-	fields := strings.Fields(line)
-	if len(fields) != 2 { //nolint:gomnd
-		return "", fmt.Errorf("%w: %s", errProtoLineFieldsCount, line)
-	}
-
-	switch fields[1] {
-	case "tcp", "udp":
-	default:
-		return "", fmt.Errorf("%w: %s", errProtocolNotSupported, fields[1])
-	}
-
-	return fields[1], nil
-}
-
-var (
-	errRemoteLineFieldsCount = errors.New("remote line has not 2 fields as expected")
-	errHostNotIP             = errors.New("host is not an an IP address")
-	errPortNotValid          = errors.New("port is not valid")
-)
-
-func extractRemote(line string) (ip net.IP, port uint16,
-	protocol string, err error) {
-	fields := strings.Fields(line)
-	n := len(fields)
-
-	if n < 2 || n > 4 {
-		return nil, 0, "", fmt.Errorf("%w: %s", errRemoteLineFieldsCount, line)
-	}
-
-	host := fields[1]
-	ip = net.ParseIP(host)
-	if ip == nil {
-		return nil, 0, "", fmt.Errorf("%w: %s", errHostNotIP, host)
-		// TODO resolve hostname once there is an option to allow it through
-		// the firewall before the VPN is up.
-	}
-
-	if n > 2 { //nolint:gomnd
-		portInt, err := strconv.Atoi(fields[2])
-		if err != nil {
-			return nil, 0, "", fmt.Errorf("%w: %s", errPortNotValid, line)
-		} else if portInt < 1 || portInt > 65535 {
-			return nil, 0, "", fmt.Errorf("%w: not between 1 and 65535: %d", errPortNotValid, portInt)
-		}
-		port = uint16(portInt)
-	}
-
-	if n > 3 { //nolint:gomnd
-		switch fields[3] {
-		case "tcp", "udp":
-			protocol = fields[3]
-		default:
-			return nil, 0, "", fmt.Errorf("%w: %s", errProtocolNotSupported, fields[3])
-		}
-	}
-
-	return ip, port, protocol, nil
-}

internal/openvpn/custom/custom_test.go

@@ -1,7 +1,6 @@
 package custom
 
 import (
-	"errors"
 	"net"
 	"os"
 	"testing"
@@ -13,7 +12,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func Test_ProcessCustomConfig(t *testing.T) {
+func Test_BuildConfig(t *testing.T) {
 	t.Parallel()
 
 	file, err := os.CreateTemp("", "")
@@ -33,7 +32,7 @@ func Test_ProcessCustomConfig(t *testing.T) {
 		Config: file.Name(),
 	}
 
-	lines, connection, err := ProcessCustomConfig(settings)
+	lines, connection, err := BuildConfig(settings)
 	assert.NoError(t, err)
 
 	expectedLines := []string{
@@ -62,348 +61,3 @@ func Test_ProcessCustomConfig(t *testing.T) {
 	}
 	assert.Equal(t, expectedConnection, connection)
 }
-
-func Test_readCustomConfigLines(t *testing.T) {
-	t.Parallel()
-
-	file, err := os.CreateTemp("", "")
-	require.NoError(t, err)
-	defer removeFile(t, file.Name())
-	defer file.Close()
-
-	_, err = file.WriteString("line one\nline two\nline three\n")
-	require.NoError(t, err)
-
-	err = file.Close()
-	require.NoError(t, err)
-
-	lines, err := readCustomConfigLines(file.Name())
-	assert.NoError(t, err)
-
-	expectedLines := []string{
-		"line one", "line two", "line three", "",
-	}
-	assert.Equal(t, expectedLines, lines)
-}
-
-func removeFile(t *testing.T, filename string) {
-	t.Helper()
-	err := os.RemoveAll(filename)
-	require.NoError(t, err)
-}
-
-func Test_modifyCustomConfig(t *testing.T) {
-	t.Parallel()
-
-	testCases := map[string]struct {
-		lines      []string
-		settings   configuration.OpenVPN
-		connection models.OpenVPNConnection
-		modified   []string
-	}{
-		"mixed": {
-			lines: []string{
-				"up bla",
-				"proto tcp",
-				"remote 5.5.5.5",
-				"cipher bla",
-				"tun-ipv6",
-				"keep me here",
-				"auth bla",
-			},
-			settings: configuration.OpenVPN{
-				User:     "user",
-				Cipher:   "cipher",
-				Auth:     "auth",
-				MSSFix:   1000,
-				ProcUser: "procuser",
-			},
-			connection: models.OpenVPNConnection{
-				IP:       net.IPv4(1, 2, 3, 4),
-				Port:     1194,
-				Protocol: constants.UDP,
-			},
-			modified: []string{
-				"keep me here",
-				"proto udp",
-				"remote 1.2.3.4 1194",
-				"mute-replay-warnings",
-				"auth-nocache",
-				"pull-filter ignore \"auth-token\"",
-				"auth-retry nointeract",
-				"suppress-timestamps",
-				"auth-user-pass /etc/openvpn/auth.conf",
-				"verb 0",
-				"data-ciphers-fallback cipher",
-				"data-ciphers cipher",
-				"auth auth",
-				"mssfix 1000",
-				"pull-filter ignore \"route-ipv6\"",
-				"pull-filter ignore \"ifconfig-ipv6\"",
-				"user procuser",
-			},
-		},
-	}
-
-	for name, testCase := range testCases {
-		testCase := testCase
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			modified := modifyCustomConfig(testCase.lines,
-				testCase.settings, testCase.connection)
-
-			assert.Equal(t, testCase.modified, modified)
-		})
-	}
-}
-
-func Test_extractConnectionFromLines(t *testing.T) {
-	t.Parallel()
-
-	testCases := map[string]struct {
-		lines      []string
-		connection models.OpenVPNConnection
-		err        error
-	}{
-		"success": {
-			lines: []string{"bla bla", "proto tcp", "remote 1.2.3.4 1194 tcp"},
-			connection: models.OpenVPNConnection{
-				IP:       net.IPv4(1, 2, 3, 4),
-				Port:     1194,
-				Protocol: constants.TCP,
-			},
-		},
-		"extraction error": {
-			lines: []string{"bla bla", "proto bad", "remote 1.2.3.4 1194 tcp"},
-			err:   errors.New("on line 2: failed extracting protocol from proto line: network protocol not supported: bad"),
-		},
-		"only use first values found": {
-			lines: []string{"proto udp", "proto tcp", "remote 1.2.3.4 443 tcp", "remote 5.2.3.4 1194 udp"},
-			connection: models.OpenVPNConnection{
-				IP:       net.IPv4(1, 2, 3, 4),
-				Port:     443,
-				Protocol: constants.UDP,
-			},
-		},
-		"no IP found": {
-			lines: []string{"proto tcp"},
-			connection: models.OpenVPNConnection{
-				Protocol: constants.TCP,
-			},
-			err: errRemoteLineNotFound,
-		},
-		"default TCP port": {
-			lines: []string{"remote 1.2.3.4", "proto tcp"},
-			connection: models.OpenVPNConnection{
-				IP:       net.IPv4(1, 2, 3, 4),
-				Port:     443,
-				Protocol: constants.TCP,
-			},
-		},
-		"default UDP port": {
-			lines: []string{"remote 1.2.3.4", "proto udp"},
-			connection: models.OpenVPNConnection{
-				IP:       net.IPv4(1, 2, 3, 4),
-				Port:     1194,
-				Protocol: constants.UDP,
-			},
-		},
-	}
-
-	for name, testCase := range testCases {
-		testCase := testCase
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			connection, err := extractConnectionFromLines(testCase.lines)
-
-			if testCase.err != nil {
-				require.Error(t, err)
-				assert.Equal(t, testCase.err.Error(), err.Error())
-			} else {
-				assert.NoError(t, err)
-			}
-
-			assert.Equal(t, testCase.connection, connection)
-		})
-	}
-}
-
-func Test_extractConnectionFromLine(t *testing.T) {
-	t.Parallel()
-
-	testCases := map[string]struct {
-		line       string
-		connection models.OpenVPNConnection
-		isErr      error
-	}{
-		"irrelevant line": {
-			line: "bla bla",
-		},
-		"extract proto error": {
-			line:  "proto bad",
-			isErr: errExtractProto,
-		},
-		"extract proto success": {
-			line: "proto tcp",
-			connection: models.OpenVPNConnection{
-				Protocol: constants.TCP,
-			},
-		},
-		"extract remote error": {
-			line:  "remote bad",
-			isErr: errExtractRemote,
-		},
-		"extract remote success": {
-			line: "remote 1.2.3.4 1194 udp",
-			connection: models.OpenVPNConnection{
-				IP:       net.IPv4(1, 2, 3, 4),
-				Port:     1194,
-				Protocol: constants.UDP,
-			},
-		},
-	}
-
-	for name, testCase := range testCases {
-		testCase := testCase
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			connection, err := extractConnectionFromLine(testCase.line)
-
-			if testCase.isErr != nil {
-				assert.ErrorIs(t, err, testCase.isErr)
-			} else {
-				assert.NoError(t, err)
-			}
-
-			assert.Equal(t, testCase.connection, connection)
-		})
-	}
-}
-
-func Test_extractProto(t *testing.T) {
-	t.Parallel()
-
-	testCases := map[string]struct {
-		line     string
-		protocol string
-		err      error
-	}{
-		"fields error": {
-			line: "proto one two",
-			err:  errors.New("proto line has not 2 fields as expected: proto one two"),
-		},
-		"bad protocol": {
-			line: "proto bad",
-			err:  errors.New("network protocol not supported: bad"),
-		},
-		"udp": {
-			line:     "proto udp",
-			protocol: constants.UDP,
-		},
-		"tcp": {
-			line:     "proto tcp",
-			protocol: constants.TCP,
-		},
-	}
-
-	for name, testCase := range testCases {
-		testCase := testCase
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			protocol, err := extractProto(testCase.line)
-
-			if testCase.err != nil {
-				require.Error(t, err)
-				assert.Equal(t, testCase.err.Error(), err.Error())
-			} else {
-				assert.NoError(t, err)
-			}
-
-			assert.Equal(t, testCase.protocol, protocol)
-		})
-	}
-}
-
-func Test_extractRemote(t *testing.T) {
-	t.Parallel()
-
-	testCases := map[string]struct {
-		line     string
-		ip       net.IP
-		port     uint16
-		protocol string
-		err      error
-	}{
-		"not enough fields": {
-			line: "remote",
-			err:  errors.New("remote line has not 2 fields as expected: remote"),
-		},
-		"too many fields": {
-			line: "remote one two three four",
-			err:  errors.New("remote line has not 2 fields as expected: remote one two three four"),
-		},
-		"host is not an IP": {
-			line: "remote somehost.com",
-			err:  errors.New("host is not an an IP address: somehost.com"),
-		},
-		"only IP host": {
-			line: "remote 1.2.3.4",
-			ip:   net.IPv4(1, 2, 3, 4),
-		},
-		"port not an integer": {
-			line: "remote 1.2.3.4 bad",
-			err:  errors.New("port is not valid: remote 1.2.3.4 bad"),
-		},
-		"port is zero": {
-			line: "remote 1.2.3.4 0",
-			err:  errors.New("port is not valid: not between 1 and 65535: 0"),
-		},
-		"port is minus one": {
-			line: "remote 1.2.3.4 -1",
-			err:  errors.New("port is not valid: not between 1 and 65535: -1"),
-		},
-		"port is over 65535": {
-			line: "remote 1.2.3.4 65536",
-			err:  errors.New("port is not valid: not between 1 and 65535: 65536"),
-		},
-		"IP host and port": {
-			line: "remote 1.2.3.4 8000",
-			ip:   net.IPv4(1, 2, 3, 4),
-			port: 8000,
-		},
-		"invalid protocol": {
-			line: "remote 1.2.3.4 8000 bad",
-			err:  errors.New("network protocol not supported: bad"),
-		},
-		"IP host and port and protocol": {
-			line:     "remote 1.2.3.4 8000 udp",
-			ip:       net.IPv4(1, 2, 3, 4),
-			port:     8000,
-			protocol: constants.UDP,
-		},
-	}
-
-	for name, testCase := range testCases {
-		testCase := testCase
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			ip, port, protocol, err := extractRemote(testCase.line)
-
-			if testCase.err != nil {
-				require.Error(t, err)
-				assert.Equal(t, testCase.err.Error(), err.Error())
-			} else {
-				assert.NoError(t, err)
-			}
-
-			assert.Equal(t, testCase.ip, ip)
-			assert.Equal(t, testCase.port, port)
-			assert.Equal(t, testCase.protocol, protocol)
-		})
-	}
-}

internal/openvpn/custom/extract.go

@@ -0,0 +1,139 @@
+package custom
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"strconv"
+	"strings"
+
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+var (
+	errRemoteLineNotFound = errors.New("remote line not found")
+)
+
+// extractConnectionFromLines always takes the first remote line only.
+func extractConnectionFromLines(lines []string) (
+	connection models.OpenVPNConnection, err error) {
+	for i, line := range lines {
+		newConnectionData, err := extractConnectionFromLine(line)
+		if err != nil {
+			return connection, fmt.Errorf("on line %d: %w", i+1, err)
+		}
+		connection.UpdateEmptyWith(newConnectionData)
+
+		if connection.Protocol != "" && connection.IP != nil {
+			break
+		}
+	}
+
+	if connection.IP == nil {
+		return connection, errRemoteLineNotFound
+	}
+
+	if connection.Protocol == "" {
+		connection.Protocol = constants.UDP
+	}
+
+	if connection.Port == 0 {
+		connection.Port = 1194
+		if connection.Protocol == constants.TCP {
+			connection.Port = 443
+		}
+	}
+
+	return connection, nil
+}
+
+var (
+	errExtractProto  = errors.New("failed extracting protocol from proto line")
+	errExtractRemote = errors.New("failed extracting protocol from remote line")
+)
+
+func extractConnectionFromLine(line string) (
+	connection models.OpenVPNConnection, err error) {
+	switch {
+	case strings.HasPrefix(line, "proto "):
+		connection.Protocol, err = extractProto(line)
+		if err != nil {
+			return connection, fmt.Errorf("%w: %s", errExtractProto, err)
+		}
+
+	// only take the first remote line
+	case strings.HasPrefix(line, "remote ") && connection.IP == nil:
+		connection.IP, connection.Port, connection.Protocol, err = extractRemote(line)
+		if err != nil {
+			return connection, fmt.Errorf("%w: %s", errExtractRemote, err)
+		}
+	}
+
+	return connection, nil
+}
+
+var (
+	errProtoLineFieldsCount = errors.New("proto line has not 2 fields as expected")
+	errProtocolNotSupported = errors.New("network protocol not supported")
+)
+
+func extractProto(line string) (protocol string, err error) {
+	fields := strings.Fields(line)
+	if len(fields) != 2 { //nolint:gomnd
+		return "", fmt.Errorf("%w: %s", errProtoLineFieldsCount, line)
+	}
+
+	switch fields[1] {
+	case "tcp", "udp":
+	default:
+		return "", fmt.Errorf("%w: %s", errProtocolNotSupported, fields[1])
+	}
+
+	return fields[1], nil
+}
+
+var (
+	errRemoteLineFieldsCount = errors.New("remote line has not 2 fields as expected")
+	errHostNotIP             = errors.New("host is not an an IP address")
+	errPortNotValid          = errors.New("port is not valid")
+)
+
+func extractRemote(line string) (ip net.IP, port uint16,
+	protocol string, err error) {
+	fields := strings.Fields(line)
+	n := len(fields)
+
+	if n < 2 || n > 4 {
+		return nil, 0, "", fmt.Errorf("%w: %s", errRemoteLineFieldsCount, line)
+	}
+
+	host := fields[1]
+	ip = net.ParseIP(host)
+	if ip == nil {
+		return nil, 0, "", fmt.Errorf("%w: %s", errHostNotIP, host)
+		// TODO resolve hostname once there is an option to allow it through
+		// the firewall before the VPN is up.
+	}
+
+	if n > 2 { //nolint:gomnd
+		portInt, err := strconv.Atoi(fields[2])
+		if err != nil {
+			return nil, 0, "", fmt.Errorf("%w: %s", errPortNotValid, line)
+		} else if portInt < 1 || portInt > 65535 {
+			return nil, 0, "", fmt.Errorf("%w: not between 1 and 65535: %d", errPortNotValid, portInt)
+		}
+		port = uint16(portInt)
+	}
+
+	if n > 3 { //nolint:gomnd
+		switch fields[3] {
+		case "tcp", "udp":
+			protocol = fields[3]
+		default:
+			return nil, 0, "", fmt.Errorf("%w: %s", errProtocolNotSupported, fields[3])
+		}
+	}
+
+	return ip, port, protocol, nil
+}

internal/openvpn/custom/extract_test.go

@@ -0,0 +1,262 @@
+package custom
+
+import (
+	"errors"
+	"net"
+	"testing"
+
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_extractConnectionFromLines(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		lines      []string
+		connection models.OpenVPNConnection
+		err        error
+	}{
+		"success": {
+			lines: []string{"bla bla", "proto tcp", "remote 1.2.3.4 1194 tcp"},
+			connection: models.OpenVPNConnection{
+				IP:       net.IPv4(1, 2, 3, 4),
+				Port:     1194,
+				Protocol: constants.TCP,
+			},
+		},
+		"extraction error": {
+			lines: []string{"bla bla", "proto bad", "remote 1.2.3.4 1194 tcp"},
+			err:   errors.New("on line 2: failed extracting protocol from proto line: network protocol not supported: bad"),
+		},
+		"only use first values found": {
+			lines: []string{"proto udp", "proto tcp", "remote 1.2.3.4 443 tcp", "remote 5.2.3.4 1194 udp"},
+			connection: models.OpenVPNConnection{
+				IP:       net.IPv4(1, 2, 3, 4),
+				Port:     443,
+				Protocol: constants.UDP,
+			},
+		},
+		"no IP found": {
+			lines: []string{"proto tcp"},
+			connection: models.OpenVPNConnection{
+				Protocol: constants.TCP,
+			},
+			err: errRemoteLineNotFound,
+		},
+		"default TCP port": {
+			lines: []string{"remote 1.2.3.4", "proto tcp"},
+			connection: models.OpenVPNConnection{
+				IP:       net.IPv4(1, 2, 3, 4),
+				Port:     443,
+				Protocol: constants.TCP,
+			},
+		},
+		"default UDP port": {
+			lines: []string{"remote 1.2.3.4", "proto udp"},
+			connection: models.OpenVPNConnection{
+				IP:       net.IPv4(1, 2, 3, 4),
+				Port:     1194,
+				Protocol: constants.UDP,
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			connection, err := extractConnectionFromLines(testCase.lines)
+
+			if testCase.err != nil {
+				require.Error(t, err)
+				assert.Equal(t, testCase.err.Error(), err.Error())
+			} else {
+				assert.NoError(t, err)
+			}
+
+			assert.Equal(t, testCase.connection, connection)
+		})
+	}
+}
+
+func Test_extractConnectionFromLine(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		line       string
+		connection models.OpenVPNConnection
+		isErr      error
+	}{
+		"irrelevant line": {
+			line: "bla bla",
+		},
+		"extract proto error": {
+			line:  "proto bad",
+			isErr: errExtractProto,
+		},
+		"extract proto success": {
+			line: "proto tcp",
+			connection: models.OpenVPNConnection{
+				Protocol: constants.TCP,
+			},
+		},
+		"extract remote error": {
+			line:  "remote bad",
+			isErr: errExtractRemote,
+		},
+		"extract remote success": {
+			line: "remote 1.2.3.4 1194 udp",
+			connection: models.OpenVPNConnection{
+				IP:       net.IPv4(1, 2, 3, 4),
+				Port:     1194,
+				Protocol: constants.UDP,
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			connection, err := extractConnectionFromLine(testCase.line)
+
+			if testCase.isErr != nil {
+				assert.ErrorIs(t, err, testCase.isErr)
+			} else {
+				assert.NoError(t, err)
+			}
+
+			assert.Equal(t, testCase.connection, connection)
+		})
+	}
+}
+
+func Test_extractProto(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		line     string
+		protocol string
+		err      error
+	}{
+		"fields error": {
+			line: "proto one two",
+			err:  errors.New("proto line has not 2 fields as expected: proto one two"),
+		},
+		"bad protocol": {
+			line: "proto bad",
+			err:  errors.New("network protocol not supported: bad"),
+		},
+		"udp": {
+			line:     "proto udp",
+			protocol: constants.UDP,
+		},
+		"tcp": {
+			line:     "proto tcp",
+			protocol: constants.TCP,
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			protocol, err := extractProto(testCase.line)
+
+			if testCase.err != nil {
+				require.Error(t, err)
+				assert.Equal(t, testCase.err.Error(), err.Error())
+			} else {
+				assert.NoError(t, err)
+			}
+
+			assert.Equal(t, testCase.protocol, protocol)
+		})
+	}
+}
+
+func Test_extractRemote(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		line     string
+		ip       net.IP
+		port     uint16
+		protocol string
+		err      error
+	}{
+		"not enough fields": {
+			line: "remote",
+			err:  errors.New("remote line has not 2 fields as expected: remote"),
+		},
+		"too many fields": {
+			line: "remote one two three four",
+			err:  errors.New("remote line has not 2 fields as expected: remote one two three four"),
+		},
+		"host is not an IP": {
+			line: "remote somehost.com",
+			err:  errors.New("host is not an an IP address: somehost.com"),
+		},
+		"only IP host": {
+			line: "remote 1.2.3.4",
+			ip:   net.IPv4(1, 2, 3, 4),
+		},
+		"port not an integer": {
+			line: "remote 1.2.3.4 bad",
+			err:  errors.New("port is not valid: remote 1.2.3.4 bad"),
+		},
+		"port is zero": {
+			line: "remote 1.2.3.4 0",
+			err:  errors.New("port is not valid: not between 1 and 65535: 0"),
+		},
+		"port is minus one": {
+			line: "remote 1.2.3.4 -1",
+			err:  errors.New("port is not valid: not between 1 and 65535: -1"),
+		},
+		"port is over 65535": {
+			line: "remote 1.2.3.4 65536",
+			err:  errors.New("port is not valid: not between 1 and 65535: 65536"),
+		},
+		"IP host and port": {
+			line: "remote 1.2.3.4 8000",
+			ip:   net.IPv4(1, 2, 3, 4),
+			port: 8000,
+		},
+		"invalid protocol": {
+			line: "remote 1.2.3.4 8000 bad",
+			err:  errors.New("network protocol not supported: bad"),
+		},
+		"IP host and port and protocol": {
+			line:     "remote 1.2.3.4 8000 udp",
+			ip:       net.IPv4(1, 2, 3, 4),
+			port:     8000,
+			protocol: constants.UDP,
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			ip, port, protocol, err := extractRemote(testCase.line)
+
+			if testCase.err != nil {
+				require.Error(t, err)
+				assert.Equal(t, testCase.err.Error(), err.Error())
+			} else {
+				assert.NoError(t, err)
+			}
+
+			assert.Equal(t, testCase.ip, ip)
+			assert.Equal(t, testCase.port, port)
+			assert.Equal(t, testCase.protocol, protocol)
+		})
+	}
+}

internal/openvpn/custom/helpers_test.go

@@ -0,0 +1,14 @@
+package custom
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func removeFile(t *testing.T, filename string) {
+	t.Helper()
+	err := os.RemoveAll(filename)
+	require.NoError(t, err)
+}

internal/openvpn/custom/modify.go

@@ -0,0 +1,65 @@
+package custom
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/qdm12/gluetun/internal/configuration"
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/qdm12/gluetun/internal/provider/utils"
+)
+
+func modifyCustomConfig(lines []string, settings configuration.OpenVPN,
+	connection models.OpenVPNConnection) (modified []string) {
+	// Remove some lines
+	for _, line := range lines {
+		switch {
+		case strings.HasPrefix(line, "up "),
+			strings.HasPrefix(line, "down "),
+			strings.HasPrefix(line, "verb "),
+			strings.HasPrefix(line, "auth-user-pass "),
+			strings.HasPrefix(line, "user "),
+			strings.HasPrefix(line, "proto "),
+			strings.HasPrefix(line, "remote "),
+			settings.Cipher != "" && strings.HasPrefix(line, "cipher "),
+			settings.Cipher != "" && strings.HasPrefix(line, "data-ciphers "),
+			settings.Auth != "" && strings.HasPrefix(line, "auth "),
+			settings.MSSFix > 0 && strings.HasPrefix(line, "mssfix "),
+			!settings.IPv6 && strings.HasPrefix(line, "tun-ipv6"):
+		default:
+			modified = append(modified, line)
+		}
+	}
+
+	// Add values
+	modified = append(modified, connection.ProtoLine())
+	modified = append(modified, connection.RemoteLine())
+	modified = append(modified, "mute-replay-warnings")
+	modified = append(modified, "auth-nocache")
+	modified = append(modified, "pull-filter ignore \"auth-token\"") // prevent auth failed loop
+	modified = append(modified, "auth-retry nointeract")
+	modified = append(modified, "suppress-timestamps")
+	if settings.User != "" {
+		modified = append(modified, "auth-user-pass "+constants.OpenVPNAuthConf)
+	}
+	modified = append(modified, "verb "+strconv.Itoa(settings.Verbosity))
+	if settings.Cipher != "" {
+		modified = append(modified, utils.CipherLines(settings.Cipher, settings.Version)...)
+	}
+	if settings.Auth != "" {
+		modified = append(modified, "auth "+settings.Auth)
+	}
+	if settings.MSSFix > 0 {
+		modified = append(modified, "mssfix "+strconv.Itoa(int(settings.MSSFix)))
+	}
+	if !settings.IPv6 {
+		modified = append(modified, `pull-filter ignore "route-ipv6"`)
+		modified = append(modified, `pull-filter ignore "ifconfig-ipv6"`)
+	}
+	if !settings.Root {
+		modified = append(modified, "user "+settings.ProcUser)
+	}
+
+	return modified
+}

internal/openvpn/custom/modify_test.go

@@ -0,0 +1,77 @@
+package custom
+
+import (
+	"net"
+	"testing"
+
+	"github.com/qdm12/gluetun/internal/configuration"
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_modifyCustomConfig(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		lines      []string
+		settings   configuration.OpenVPN
+		connection models.OpenVPNConnection
+		modified   []string
+	}{
+		"mixed": {
+			lines: []string{
+				"up bla",
+				"proto tcp",
+				"remote 5.5.5.5",
+				"cipher bla",
+				"tun-ipv6",
+				"keep me here",
+				"auth bla",
+			},
+			settings: configuration.OpenVPN{
+				User:     "user",
+				Cipher:   "cipher",
+				Auth:     "auth",
+				MSSFix:   1000,
+				ProcUser: "procuser",
+			},
+			connection: models.OpenVPNConnection{
+				IP:       net.IPv4(1, 2, 3, 4),
+				Port:     1194,
+				Protocol: constants.UDP,
+			},
+			modified: []string{
+				"keep me here",
+				"proto udp",
+				"remote 1.2.3.4 1194",
+				"mute-replay-warnings",
+				"auth-nocache",
+				"pull-filter ignore \"auth-token\"",
+				"auth-retry nointeract",
+				"suppress-timestamps",
+				"auth-user-pass /etc/openvpn/auth.conf",
+				"verb 0",
+				"data-ciphers-fallback cipher",
+				"data-ciphers cipher",
+				"auth auth",
+				"mssfix 1000",
+				"pull-filter ignore \"route-ipv6\"",
+				"pull-filter ignore \"ifconfig-ipv6\"",
+				"user procuser",
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			modified := modifyCustomConfig(testCase.lines,
+				testCase.settings, testCase.connection)
+
+			assert.Equal(t, testCase.modified, modified)
+		})
+	}
+}

internal/openvpn/custom/read.go

@@ -0,0 +1,27 @@
+package custom
+
+import (
+	"io"
+	"os"
+	"strings"
+)
+
+func readCustomConfigLines(filepath string) (
+	lines []string, err error) {
+	file, err := os.Open(filepath)
+	if err != nil {
+		return nil, err
+	}
+
+	b, err := io.ReadAll(file)
+	if err != nil {
+		_ = file.Close()
+		return nil, err
+	}
+
+	if err := file.Close(); err != nil {
+		return nil, err
+	}
+
+	return strings.Split(string(b), "\n"), nil
+}

internal/openvpn/custom/read_test.go

@@ -0,0 +1,32 @@
+package custom
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_readCustomConfigLines(t *testing.T) {
+	t.Parallel()
+
+	file, err := os.CreateTemp("", "")
+	require.NoError(t, err)
+	defer removeFile(t, file.Name())
+	defer file.Close()
+
+	_, err = file.WriteString("line one\nline two\nline three\n")
+	require.NoError(t, err)
+
+	err = file.Close()
+	require.NoError(t, err)
+
+	lines, err := readCustomConfigLines(file.Name())
+	assert.NoError(t, err)
+
+	expectedLines := []string{
+		"line one", "line two", "line three", "",
+	}
+	assert.Equal(t, expectedLines, lines)
+}

internal/openvpn/run.go

@@ -37,7 +37,7 @@ func (l *Loop) Run(ctx context.Context, done chan<- struct{}) {
 				lines = providerConf.BuildConf(connection, openVPNSettings)
 			}
 		} else {
-			lines, connection, err = custom.ProcessCustomConfig(openVPNSettings)
+			lines, connection, err = custom.BuildConfig(openVPNSettings)
 		}
 		if err != nil {
 			l.crashed(ctx, err)