Maint: tun package to handle tun device operations

- Moved from openvpn package to tun package
- TUN check verifies Rdev value
- TUN create
- Inject as interface to main function
- Add integration test
- Clearer log message for end users if tun device does not exist
- Remove unix package (unneeded for tests)
- Remove tun file opening at the end of tun file creation
- Do not mock unix.Mkdev (no OS operation)
- Remove Tun operations from OpenVPN configurator

cmd/gluetun/main.go

@@ -29,7 +29,7 @@ import (
 	"github.com/qdm12/gluetun/internal/server"
 	"github.com/qdm12/gluetun/internal/shadowsocks"
 	"github.com/qdm12/gluetun/internal/storage"
-	"github.com/qdm12/gluetun/internal/unix"
+	"github.com/qdm12/gluetun/internal/tun"
 	"github.com/qdm12/gluetun/internal/updater"
 	"github.com/qdm12/golibs/command"
 	"github.com/qdm12/golibs/logging"
@@ -67,14 +67,14 @@ func main() {
 	})
 
 	args := os.Args
-	unix := unix.New()
+	tun := tun.New()
 	cli := cli.New()
 	env := params.NewEnv()
 	cmder := command.NewCmder()
 
 	errorCh := make(chan error)
 	go func() {
-		errorCh <- _main(ctx, buildInfo, args, logger, env, unix, cmder, cli)
+		errorCh <- _main(ctx, buildInfo, args, logger, env, tun, cmder, cli)
 	}()
 
 	select {
@@ -113,7 +113,7 @@ var (
 //nolint:gocognit,gocyclo
 func _main(ctx context.Context, buildInfo models.BuildInformation,
 	args []string, logger logging.ParentLogger, env params.Env,
-	unix unix.Unix, cmder command.RunStarter, cli cli.CLIer) error {
+	tun tun.Interface, cmder command.RunStarter, cli cli.CLIer) error {
 	if len(args) > 1 { // cli operation
 		switch args[1] {
 		case "healthcheck":
@@ -135,7 +135,7 @@ func _main(ctx context.Context, buildInfo models.BuildInformation,
 	alpineConf := alpine.New()
 	ovpnConf := openvpn.NewConfigurator(
 		logger.NewChild(logging.Settings{Prefix: "openvpn configurator: "}),
-		unix, cmder)
+		cmder)
 	dnsCrypto := dnscrypto.New(httpClient, "", "")
 	const cacertsPath = "/etc/ssl/certs/ca-certificates.crt"
 	dnsConf := unbound.NewConfigurator(nil, cmder, dnsCrypto,
@@ -270,9 +270,9 @@ func _main(ctx context.Context, buildInfo models.BuildInformation,
 		return err
 	}
 
-	if err := ovpnConf.CheckTUN(); err != nil {
+	if err := tun.Check(constants.TunnelDevice); err != nil {
-		logger.Warn(err.Error())
+		logger.Info(err.Error() + "; creating it...")
-		err = ovpnConf.CreateTUN()
+		err = tun.Create(constants.TunnelDevice)
 		if err != nil {
 			return err
 		}

internal/openvpn/openvpn.go

@@ -4,7 +4,6 @@ package openvpn
 
 import (
 	"github.com/qdm12/gluetun/internal/constants"
-	"github.com/qdm12/gluetun/internal/unix"
 	"github.com/qdm12/golibs/command"
 	"github.com/qdm12/golibs/logging"
 )
@@ -12,7 +11,6 @@ import (
 type Configurator interface {
 	VersionGetter
 	AuthWriter
-	TUNCheckCreater
 	Starter
 }
 
@@ -24,18 +22,14 @@ type StarterAuthWriter interface {
 type configurator struct {
 	logger       logging.Logger
 	cmder        command.RunStarter
-	unix         unix.Unix
 	authFilePath string
-	tunDevPath   string
 }
 
-func NewConfigurator(logger logging.Logger, unix unix.Unix,
+func NewConfigurator(logger logging.Logger,
 	cmder command.RunStarter) Configurator {
 	return &configurator{
 		logger:       logger,
 		cmder:        cmder,
-		unix:         unix,
 		authFilePath: constants.OpenVPNAuthConf,
-		tunDevPath:   constants.TunnelDevice,
 	}
 }

internal/openvpn/tun.go

@@ -1,61 +0,0 @@
-package openvpn
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-
-	"github.com/qdm12/gluetun/internal/unix"
-)
-
-type TUNCheckCreater interface {
-	TUNChecker
-	TUNCreater
-}
-
-type TUNChecker interface {
-	CheckTUN() error
-}
-
-// CheckTUN checks the tunnel device is present and accessible.
-func (c *configurator) CheckTUN() error {
-	c.logger.Info("checking for device " + c.tunDevPath)
-	f, err := os.OpenFile(c.tunDevPath, os.O_RDWR, 0)
-	if err != nil {
-		return fmt.Errorf("TUN device is not available: %w", err)
-	}
-	if err := f.Close(); err != nil {
-		c.logger.Warn("Could not close TUN device file: " + err.Error())
-	}
-	return nil
-}
-
-type TUNCreater interface {
-	CreateTUN() error
-}
-
-func (c *configurator) CreateTUN() error {
-	c.logger.Info("creating " + c.tunDevPath)
-
-	parentDir := filepath.Dir(c.tunDevPath)
-	if err := os.MkdirAll(parentDir, 0751); err != nil { //nolint:gomnd
-		return err
-	}
-
-	const (
-		major = 10
-		minor = 200
-	)
-	dev := c.unix.Mkdev(major, minor)
-	if err := c.unix.Mknod(c.tunDevPath, unix.S_IFCHR, int(dev)); err != nil {
-		return err
-	}
-
-	const readWriteAllPerms os.FileMode = 0666
-	file, err := os.OpenFile(c.tunDevPath, os.O_WRONLY, readWriteAllPerms)
-	if err != nil {
-		return err
-	}
-
-	return file.Close()
-}

internal/tun/check.go

@@ -0,0 +1,51 @@
+package tun
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"syscall"
+)
+
+type Checker interface {
+	Check(path string) error
+}
+
+var (
+	ErrTUNNotAvailable = errors.New("TUN device is not available")
+	ErrTUNStat         = errors.New("cannot stat TUN file")
+	ErrTUNInfo         = errors.New("cannot get syscall stat info of TUN file")
+	ErrTUNBadRdev      = errors.New("TUN file has an unexpected rdev")
+	ErrTUNClose        = errors.New("cannot close TUN device")
+)
+
+// Check checks the tunnel device specified by path is present and accessible.
+func (t *Tun) Check(path string) error {
+	f, err := os.OpenFile(path, os.O_RDWR, 0)
+	if err != nil {
+		return fmt.Errorf("%w: %s", ErrTUNNotAvailable, err)
+	}
+	defer f.Close()
+
+	info, err := f.Stat()
+	if err != nil {
+		return fmt.Errorf("%w: %s", ErrTUNStat, err)
+	}
+
+	sys, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		return ErrTUNInfo
+	}
+
+	const expectedRdev = 2760 // corresponds to major 10 and minor 200
+	if sys.Rdev != expectedRdev {
+		return fmt.Errorf("%w: %d instead of expected %d",
+			ErrTUNBadRdev, sys.Rdev, expectedRdev)
+	}
+
+	if err := f.Close(); err != nil {
+		return fmt.Errorf("%w: %s", ErrTUNClose, err)
+	}
+
+	return nil
+}

internal/tun/create.go

@@ -0,0 +1,38 @@
+package tun
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"golang.org/x/sys/unix"
+)
+
+type Creator interface {
+	Create(path string) error
+}
+
+var (
+	ErrMknod = errors.New("cannot create TUN device file node")
+)
+
+// Create creates a TUN device at the path specified.
+func (t *Tun) Create(path string) error {
+	parentDir := filepath.Dir(path)
+	if err := os.MkdirAll(parentDir, 0751); err != nil { //nolint:gomnd
+		return err
+	}
+
+	const (
+		major = 10
+		minor = 200
+	)
+	dev := unix.Mkdev(major, minor)
+	err := t.mknod(path, unix.S_IFCHR, int(dev))
+	if err != nil {
+		return fmt.Errorf("%w: %s", ErrMknod, err)
+	}
+
+	return nil
+}

internal/tun/tun.go

@@ -0,0 +1,20 @@
+package tun
+
+import "golang.org/x/sys/unix"
+
+var _ Interface = (*Tun)(nil)
+
+type Interface interface {
+	Checker
+	Creator
+}
+
+type Tun struct {
+	mknod func(path string, mode uint32, dev int) (err error)
+}
+
+func New() *Tun {
+	return &Tun{
+		mknod: unix.Mknod,
+	}
+}

internal/tun/tun_test.go

@@ -0,0 +1,68 @@
+package tun
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_Tun(t *testing.T) {
+	t.Parallel()
+
+	path := getTempPath(t)
+
+	tun := New()
+
+	defer func() {
+		err := os.RemoveAll(path)
+		require.NoError(t, err)
+	}()
+
+	// No file check fail
+	err := tun.Check(path)
+	require.Error(t, err)
+	expectedMessage := "TUN device is not available: open " + path + ": no such file or directory"
+	require.Equal(t, expectedMessage, err.Error())
+
+	// Create simple file
+	file, err := os.Create(path)
+	require.NoError(t, err)
+	err = file.Close()
+	require.NoError(t, err)
+
+	// Simple file check fail
+	err = tun.Check(path)
+	require.Error(t, err)
+	expectedMessage = "TUN file has an unexpected rdev: 0 instead of expected 2760"
+	require.Equal(t, expectedMessage, err.Error())
+
+	// Create TUN device fail as file exists
+	err = tun.Create(path)
+	require.Error(t, err)
+	require.Equal(t, "cannot create TUN device file node: file exists", err.Error())
+
+	// Remove simple file
+	err = os.Remove(path)
+	require.NoError(t, err)
+
+	// Create TUN device success
+	err = tun.Create(path)
+	require.NoError(t, err)
+
+	// Check TUN device success
+	err = tun.Check(path)
+	require.NoError(t, err)
+}
+
+func getTempPath(t *testing.T) (path string) {
+	t.Helper()
+	file, err := os.CreateTemp("", "")
+	require.NoError(t, err)
+	path = file.Name()
+	err = file.Close()
+	require.NoError(t, err)
+	err = os.Remove(path)
+	require.NoError(t, err)
+	return path
+}

internal/unix/constants.go

@@ -1,9 +0,0 @@
-package unix
-
-import sysunix "golang.org/x/sys/unix"
-
-// Constants used for convenience so "os" does not have to be imported
-
-const (
-	S_IFCHR = sysunix.S_IFCHR //nolint:revive
-)

internal/unix/mock_unix/unix.go

@@ -1,61 +0,0 @@
-// Code generated by MockGen. DO NOT EDIT.
-// Source: github.com/qdm12/gluetun/internal/unix (interfaces: Unix)
-
-// Package mock_unix is a generated GoMock package.
-package mock_unix
-
-import (
-	gomock "github.com/golang/mock/gomock"
-	reflect "reflect"
-)
-
-// MockUnix is a mock of Unix interface
-type MockUnix struct {
-	ctrl     *gomock.Controller
-	recorder *MockUnixMockRecorder
-}
-
-// MockUnixMockRecorder is the mock recorder for MockUnix
-type MockUnixMockRecorder struct {
-	mock *MockUnix
-}
-
-// NewMockUnix creates a new mock instance
-func NewMockUnix(ctrl *gomock.Controller) *MockUnix {
-	mock := &MockUnix{ctrl: ctrl}
-	mock.recorder = &MockUnixMockRecorder{mock}
-	return mock
-}
-
-// EXPECT returns an object that allows the caller to indicate expected use
-func (m *MockUnix) EXPECT() *MockUnixMockRecorder {
-	return m.recorder
-}
-
-// Mkdev mocks base method
-func (m *MockUnix) Mkdev(arg0, arg1 uint32) uint64 {
-	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "Mkdev", arg0, arg1)
-	ret0, _ := ret[0].(uint64)
-	return ret0
-}
-
-// Mkdev indicates an expected call of Mkdev
-func (mr *MockUnixMockRecorder) Mkdev(arg0, arg1 interface{}) *gomock.Call {
-	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Mkdev", reflect.TypeOf((*MockUnix)(nil).Mkdev), arg0, arg1)
-}
-
-// Mknod mocks base method
-func (m *MockUnix) Mknod(arg0 string, arg1 uint32, arg2 int) error {
-	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "Mknod", arg0, arg1, arg2)
-	ret0, _ := ret[0].(error)
-	return ret0
-}
-
-// Mknod indicates an expected call of Mknod
-func (mr *MockUnixMockRecorder) Mknod(arg0, arg1, arg2 interface{}) *gomock.Call {
-	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Mknod", reflect.TypeOf((*MockUnix)(nil).Mknod), arg0, arg1, arg2)
-}

internal/unix/unix.go

@@ -1,26 +0,0 @@
-// Package unix defines interfaces to interact with Unix related objects.
-// Its primary use is to be used in tests.
-package unix
-
-import sysunix "golang.org/x/sys/unix"
-
-//go:generate mockgen -destination=mock_$GOPACKAGE/$GOFILE . Unix
-
-type Unix interface {
-	Mkdev(major uint32, minor uint32) uint64
-	Mknod(path string, mode uint32, dev int) (err error)
-}
-
-func New() Unix {
-	return &unix{}
-}
-
-type unix struct{}
-
-func (u *unix) Mkdev(major uint32, minor uint32) uint64 {
-	return sysunix.Mkdev(major, minor)
-}
-
-func (u *unix) Mknod(path string, mode uint32, dev int) (err error) {
-	return sysunix.Mknod(path, mode, dev)
-}