Maint: rework OpenVPN custom configuration code

- Refactor code and errors returned
- Add unit tests
- Make custom config code independent from loop

internal/models/openvpn.go

@@ -26,3 +26,19 @@ func (o OpenVPNConnection) RemoteLine() (line string) {
 func (o OpenVPNConnection) ProtoLine() (line string) {
 	return "proto " + o.Protocol
 }
+
+// UpdateEmptyWith updates each field of the connection where the value is not set.
+func (o *OpenVPNConnection) UpdateEmptyWith(connection OpenVPNConnection) {
+	if o.IP == nil {
+		o.IP = connection.IP
+	}
+	if o.Port == 0 {
+		o.Port = connection.Port
+	}
+	if o.Protocol == "" {
+		o.Protocol = connection.Protocol
+	}
+	if o.Hostname == "" {
+		o.Hostname = connection.Hostname
+	}
+}

internal/openvpn/custom.go

@@ -15,23 +15,25 @@ import (
 	"github.com/qdm12/gluetun/internal/provider/utils"
 )
 
-var errProcessCustomConfig = errors.New("cannot process custom config")
+var (
+	errReadCustomConfig  = errors.New("cannot read custom configuration file")
+	errExtractConnection = errors.New("cannot extract connection from custom configuration file")
+)
 
-func (l *Loop) processCustomConfig(settings configuration.OpenVPN) (
+func processCustomConfig(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", errProcessCustomConfig, err)
+		return nil, connection, fmt.Errorf("%w: %s", errReadCustomConfig, err)
 	}
 
-	lines = modifyCustomConfig(lines, settings)
-
 	connection, err = extractConnectionFromLines(lines)
 	if err != nil {
-		return nil, connection, fmt.Errorf("%w: %s", errProcessCustomConfig, err)
+		return nil, connection, fmt.Errorf("%w: %s", errExtractConnection, err)
 	}
 
-	lines = setConnectionToLines(lines, connection)
+	lines = modifyCustomConfig(lines, settings, connection)
+
 	return lines, connection, nil
 }
 
@@ -41,10 +43,10 @@ func readCustomConfigLines(filepath string) (
 	if err != nil {
 		return nil, err
 	}
-	defer file.Close()
 
 	b, err := io.ReadAll(file)
 	if err != nil {
+		_ = file.Close()
 		return nil, err
 	}
 
@@ -55,8 +57,8 @@ func readCustomConfigLines(filepath string) (
 	return strings.Split(string(b), "\n"), nil
 }
 
-func modifyCustomConfig(lines []string,
+func modifyCustomConfig(lines []string, settings configuration.OpenVPN,
-	settings configuration.OpenVPN) (modified []string) {
+	connection models.OpenVPNConnection) (modified []string) {
 	// Remove some lines
 	for _, line := range lines {
 		switch {
@@ -65,9 +67,11 @@ func modifyCustomConfig(lines []string,
 			strings.HasPrefix(line, "verb "),
 			strings.HasPrefix(line, "auth-user-pass "),
 			strings.HasPrefix(line, "user "),
-			len(settings.Cipher) > 0 && strings.HasPrefix(line, "cipher "),
+			strings.HasPrefix(line, "proto "),
-			len(settings.Cipher) > 0 && strings.HasPrefix(line, "data-ciphers"),
+			strings.HasPrefix(line, "remote "),
-			len(settings.Auth) > 0 && strings.HasPrefix(line, "auth "),
+			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:
@@ -76,6 +80,8 @@ func modifyCustomConfig(lines []string,
 	}
 
 	// 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
@@ -85,10 +91,10 @@ func modifyCustomConfig(lines []string,
 		modified = append(modified, "auth-user-pass "+constants.OpenVPNAuthConf)
 	}
 	modified = append(modified, "verb "+strconv.Itoa(settings.Verbosity))
-	if len(settings.Cipher) > 0 {
+	if settings.Cipher != "" {
 		modified = append(modified, utils.CipherLines(settings.Cipher, settings.Version)...)
 	}
-	if len(settings.Auth) > 0 {
+	if settings.Auth != "" {
 		modified = append(modified, "auth "+settings.Auth)
 	}
 	if settings.MSSFix > 0 {
@@ -105,64 +111,19 @@ func modifyCustomConfig(lines []string,
 	return modified
 }
 
-var errExtractConnection = errors.New("cannot extract connection")
+var (
+	errRemoteLineNotFound = errors.New("remote line not found")
+)
 
 // extractConnectionFromLines always takes the first remote line only.
-func extractConnectionFromLines(lines []string) ( //nolint:gocognit
+func extractConnectionFromLines(lines []string) (
 	connection models.OpenVPNConnection, err error) {
-	for _, line := range lines {
+	for i, line := range lines {
-		switch {
+		newConnectionData, err := extractConnectionFromLine(line)
-		case strings.HasPrefix(line, "proto "):
+		if err != nil {
-			fields := strings.Fields(line)
+			return connection, fmt.Errorf("on line %d: %w", i+1, err)
-			if n := len(fields); n != 2 { //nolint:gomnd
-				return connection, fmt.Errorf(
-					"%w: proto line has %d fields instead of 2: %s",
-					errExtractConnection, n, line)
-			}
-			connection.Protocol = fields[1]
-
-		// only take the first remote line
-		case strings.HasPrefix(line, "remote ") && connection.IP == nil:
-			fields := strings.Fields(line)
-			n := len(fields)
-			//nolint:gomnd
-			if n < 2 {
-				return connection, fmt.Errorf(
-					"%w: remote line has not enough fields: %s",
-					errExtractConnection, line)
-			}
-
-			host := fields[1]
-			if ip := net.ParseIP(host); ip != nil {
-				connection.IP = ip
-			} else {
-				return connection, fmt.Errorf(
-					"%w: for now, the remote line must contain an IP adddress: %s",
-					errExtractConnection, line)
-				// TODO resolve hostname once there is an option to allow it through
-				// the firewall before the VPN is up.
-			}
-
-			if n > 2 { //nolint:gomnd
-				port, err := strconv.Atoi(fields[2])
-				if err != nil {
-					return connection, fmt.Errorf(
-						"%w: remote line has an invalid port: %s",
-						errExtractConnection, line)
-				}
-				connection.Port = uint16(port)
-			}
-
-			if n > 3 { //nolint:gomnd
-				connection.Protocol = strings.ToLower(fields[3])
-			}
-
-			if n > 4 { //nolint:gomnd
-				return connection, fmt.Errorf(
-					"%w: remote line has too many fields: %s",
-					errExtractConnection, line)
-			}
 		}
+		connection.UpdateEmptyWith(newConnectionData)
 
 		if connection.Protocol != "" && connection.IP != nil {
 			break
@@ -170,40 +131,109 @@ func extractConnectionFromLines(lines []string) ( //nolint:gocognit
 	}
 
 	if connection.IP == nil {
-		return connection, fmt.Errorf("%w: remote line not found", errExtractConnection)
+		return connection, errRemoteLineNotFound
 	}
 
-	switch connection.Protocol {
+	if connection.Protocol == "" {
-	case "":
+		connection.Protocol = constants.UDP
-		connection.Protocol = "udp"
-	case "tcp", "udp":
-	default:
-		return connection, fmt.Errorf("%w: network protocol not supported: %s", errExtractConnection, connection.Protocol)
 	}
 
 	if connection.Port == 0 {
-		if connection.Protocol == "tcp" {
+		connection.Port = 1194
-			const defaultPort uint16 = 443
+		if connection.Protocol == constants.TCP {
-			connection.Port = defaultPort
+			connection.Port = 443
-		} else {
-			const defaultPort uint16 = 1194
-			connection.Port = defaultPort
 		}
 	}
 
 	return connection, nil
 }
 
-func setConnectionToLines(lines []string, connection models.OpenVPNConnection) (modified []string) {
+var (
-	for i, line := range lines {
+	errExtractProto  = errors.New("failed extracting protocol from proto line")
-		switch {
+	errExtractRemote = errors.New("failed extracting protocol from remote line")
-		case strings.HasPrefix(line, "proto "):
+)
-			lines[i] = connection.ProtoLine()
 
-		case strings.HasPrefix(line, "remote "):
+func extractConnectionFromLine(line string) (
-			lines[i] = connection.RemoteLine()
+	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 lines
+	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_test.go

@@ -0,0 +1,409 @@
+package openvpn
+
+import (
+	"errors"
+	"net"
+	"os"
+	"testing"
+
+	"github.com/qdm12/gluetun/internal/configuration"
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_processCustomConfig(t *testing.T) {
+	t.Parallel()
+
+	file, err := os.CreateTemp("", "")
+	require.NoError(t, err)
+	defer removeFile(t, file.Name())
+	defer file.Close()
+
+	_, err = file.WriteString("remote 1.9.8.7\nkeep me\ncipher remove")
+	require.NoError(t, err)
+
+	err = file.Close()
+	require.NoError(t, err)
+
+	settings := configuration.OpenVPN{
+		Cipher: "cipher",
+		MSSFix: 999,
+		Config: file.Name(),
+	}
+
+	lines, connection, err := processCustomConfig(settings)
+	assert.NoError(t, err)
+
+	expectedLines := []string{
+		"keep me",
+		"proto udp",
+		"remote 1.9.8.7 1194",
+		"mute-replay-warnings",
+		"auth-nocache",
+		"pull-filter ignore \"auth-token\"",
+		"auth-retry nointeract",
+		"suppress-timestamps",
+		"verb 0",
+		"data-ciphers-fallback cipher",
+		"data-ciphers cipher",
+		"mssfix 999",
+		"pull-filter ignore \"route-ipv6\"",
+		"pull-filter ignore \"ifconfig-ipv6\"",
+		"user ",
+	}
+	assert.Equal(t, expectedLines, lines)
+
+	expectedConnection := models.OpenVPNConnection{
+		IP:       net.IPv4(1, 9, 8, 7),
+		Port:     1194,
+		Protocol: constants.UDP,
+	}
+	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/run.go

@@ -36,7 +36,7 @@ func (l *Loop) Run(ctx context.Context, done chan<- struct{}) {
 				lines = providerConf.BuildConf(connection, openVPNSettings)
 			}
 		} else {
-			lines, connection, err = l.processCustomConfig(openVPNSettings)
+			lines, connection, err = processCustomConfig(openVPNSettings)
 		}
 		if err != nil {
 			l.crashed(ctx, err)