tun: only call .Fd() once

Doing so tends to make the tunnel blocking, so we only retrieve it once
before we call SetNonblock, and then cache the result.

tun/tun_darwin.go

@@ -37,7 +37,8 @@ type sockaddrCtl struct {
 
 type nativeTun struct {
 	name        string
-	fd          *os.File
+	tunFile     *os.File
+	fd          uintptr
 	rwcancel    *rwcancel.RWCancel
 	events      chan TUNEvent
 	errors      chan error
@@ -171,14 +172,15 @@ func CreateTUN(name string, mtu int) (TUNDevice, error) {
 func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 
 	tun := &nativeTun{
-		fd:     file,
+		tunFile: file,
-		events: make(chan TUNEvent, 10),
+		fd:      file.Fd(),
-		errors: make(chan error, 1),
+		events:  make(chan TUNEvent, 10),
+		errors:  make(chan error, 1),
 	}
 
 	name, err := tun.Name()
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
@@ -190,19 +192,19 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 		return iface.Index, nil
 	}()
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
-	tun.rwcancel, err = rwcancel.NewRWCancel(int(file.Fd()))
+	tun.rwcancel, err = rwcancel.NewRWCancel(int(tun.fd))
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
 	tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
@@ -226,7 +228,7 @@ func (tun *nativeTun) Name() (string, error) {
 
 	_, _, errno := unix.Syscall6(
 		unix.SYS_GETSOCKOPT,
-		uintptr(tun.fd.Fd()),
+		uintptr(tun.fd),
 		2, /* #define SYSPROTO_CONTROL 2 */
 		2, /* #define UTUN_OPT_IFNAME 2 */
 		uintptr(unsafe.Pointer(&ifName)),
@@ -241,7 +243,7 @@ func (tun *nativeTun) Name() (string, error) {
 }
 
 func (tun *nativeTun) File() *os.File {
-	return tun.fd
+	return tun.tunFile
 }
 
 func (tun *nativeTun) Events() chan TUNEvent {
@@ -254,7 +256,7 @@ func (tun *nativeTun) doRead(buff []byte, offset int) (int, error) {
 		return 0, err
 	default:
 		buff := buff[offset-4:]
-		n, err := tun.fd.Read(buff[:])
+		n, err := tun.tunFile.Read(buff[:])
 		if n < 4 {
 			return 0, err
 		}
@@ -294,13 +296,13 @@ func (tun *nativeTun) Write(buff []byte, offset int) (int, error) {
 
 	// write
 
-	return tun.fd.Write(buff)
+	return tun.tunFile.Write(buff)
 }
 
 func (tun *nativeTun) Close() error {
 	var err3 error
 	err1 := tun.rwcancel.Cancel()
-	err2 := tun.fd.Close()
+	err2 := tun.tunFile.Close()
 	if tun.routeSocket != -1 {
 		unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)
 		err3 = unix.Close(tun.routeSocket)

tun/tun_freebsd.go

@@ -51,7 +51,8 @@ type ifstat struct {
 
 type nativeTun struct {
 	name        string
-	fd          *os.File
+	tunFile     *os.File
+	fd          uintptr
 	rwcancel    *rwcancel.RWCancel
 	events      chan TUNEvent
 	errors      chan error
@@ -237,15 +238,15 @@ func CreateTUN(name string, mtu int) (TUNDevice, error) {
 		return nil, fmt.Errorf("interface %s already exists", name)
 	}
 
-	tunfile, err := os.OpenFile("/dev/tun", unix.O_RDWR, 0)
+	tunFile, err := os.OpenFile("/dev/tun", unix.O_RDWR, 0)
 
 	if err != nil {
 		return nil, err
 	}
-	tunfd := tunfile.Fd()
+	tunfd := tunFile.Fd()
 	assignedName, err := tunName(tunfd)
 	if err != nil {
-		tunfile.Close()
+		tunFile.Close()
 		return nil, err
 	}
 
@@ -293,25 +294,26 @@ func CreateTUN(name string, mtu int) (TUNDevice, error) {
 		uintptr(unsafe.Pointer(&ifr)),
 	)
 	if errno != 0 {
-		tunfile.Close()
+		tunFile.Close()
 		tunDestroy(name)
 		return nil, fmt.Errorf("failed to rename %s to %s: %s", assignedName, name, errno.Error())
 	}
 
-	return CreateTUNFromFile(tunfile, mtu)
+	return CreateTUNFromFile(tunFile, mtu)
 }
 
 func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 
 	tun := &nativeTun{
-		fd:     file,
+		tunFile: file,
-		events: make(chan TUNEvent, 10),
+		fd:      file.Fd(),
-		errors: make(chan error, 1),
+		events:  make(chan TUNEvent, 10),
+		errors:  make(chan error, 1),
 	}
 
 	name, err := tun.Name()
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
@@ -323,19 +325,19 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 		return iface.Index, nil
 	}()
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
-	tun.rwcancel, err = rwcancel.NewRWCancel(int(file.Fd()))
+	tun.rwcancel, err = rwcancel.NewRWCancel(int(tun.fd))
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
 	tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
@@ -351,7 +353,7 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 }
 
 func (tun *nativeTun) Name() (string, error) {
-	name, err := tunName(tun.fd.Fd())
+	name, err := tunName(tun.fd)
 	if err != nil {
 		return "", err
 	}
@@ -360,7 +362,7 @@ func (tun *nativeTun) Name() (string, error) {
 }
 
 func (tun *nativeTun) File() *os.File {
-	return tun.fd
+	return tun.tunFile
 }
 
 func (tun *nativeTun) Events() chan TUNEvent {
@@ -373,7 +375,7 @@ func (tun *nativeTun) doRead(buff []byte, offset int) (int, error) {
 		return 0, err
 	default:
 		buff := buff[offset-4:]
-		n, err := tun.fd.Read(buff[:])
+		n, err := tun.tunFile.Read(buff[:])
 		if n < 4 {
 			return 0, err
 		}
@@ -413,13 +415,13 @@ func (tun *nativeTun) Write(buff []byte, offset int) (int, error) {
 
 	// write
 
-	return tun.fd.Write(buff)
+	return tun.tunFile.Write(buff)
 }
 
 func (tun *nativeTun) Close() error {
 	var err4 error
 	err1 := tun.rwcancel.Cancel()
-	err2 := tun.fd.Close()
+	err2 := tun.tunFile.Close()
 	err3 := tunDestroy(tun.name)
 	if tun.routeSocket != -1 {
 		unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)

tun/tun_linux.go

@@ -29,7 +29,8 @@ const (
 )
 
 type nativeTun struct {
-	fd                      *os.File
+	tunFile                 *os.File
+	fd                      uintptr
 	fdCancel                *rwcancel.RWCancel
 	index                   int32         // if index
 	name                    string        // name of interface
@@ -43,7 +44,7 @@ type nativeTun struct {
 }
 
 func (tun *nativeTun) File() *os.File {
-	return tun.fd
+	return tun.tunFile
 }
 
 func (tun *nativeTun) routineHackListener() {
@@ -51,7 +52,7 @@ func (tun *nativeTun) routineHackListener() {
 	/* This is needed for the detection to work across network namespaces
 	 * If you are reading this and know a better method, please get in touch.
 	 */
-	fd := int(tun.fd.Fd())
+	fd := int(tun.fd)
 	for {
 		_, err := unix.Write(fd, nil)
 		switch err {
@@ -266,7 +267,7 @@ func (tun *nativeTun) Name() (string, error) {
 	var ifr [ifReqSize]byte
 	_, _, errno := unix.Syscall(
 		unix.SYS_IOCTL,
-		tun.fd.Fd(),
+		tun.fd,
 		uintptr(unix.TUNGETIFF),
 		uintptr(unsafe.Pointer(&ifr[0])),
 	)
@@ -307,7 +308,7 @@ func (tun *nativeTun) Write(buff []byte, offset int) (int, error) {
 
 	// write
 
-	return tun.fd.Write(buff)
+	return tun.tunFile.Write(buff)
 }
 
 func (tun *nativeTun) doRead(buff []byte, offset int) (int, error) {
@@ -316,10 +317,10 @@ func (tun *nativeTun) doRead(buff []byte, offset int) (int, error) {
 		return 0, err
 	default:
 		if tun.nopi {
-			return tun.fd.Read(buff[offset:])
+			return tun.tunFile.Read(buff[offset:])
 		} else {
 			buff := buff[offset-4:]
-			n, err := tun.fd.Read(buff[:])
+			n, err := tun.tunFile.Read(buff[:])
 			if n < 4 {
 				return 0, err
 			}
@@ -354,7 +355,7 @@ func (tun *nativeTun) Close() error {
 	} else if tun.events != nil {
 		close(tun.events)
 	}
-	err2 := tun.fd.Close()
+	err2 := tun.tunFile.Close()
 	err3 := tun.fdCancel.Cancel()
 
 	if err1 != nil {
@@ -413,23 +414,24 @@ func CreateTUN(name string, mtu int) (TUNDevice, error) {
 
 func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 	tun := &nativeTun{
-		fd:                      file,
+		tunFile:                 file,
+		fd:                      file.Fd(),
 		events:                  make(chan TUNEvent, 5),
 		errors:                  make(chan error, 5),
 		statusListenersShutdown: make(chan struct{}),
-		nopi: false,
+		nopi:                    false,
 	}
 	var err error
 
-	tun.fdCancel, err = rwcancel.NewRWCancel(int(file.Fd()))
+	tun.fdCancel, err = rwcancel.NewRWCancel(int(tun.fd))
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
 	_, err = tun.Name()
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
@@ -442,12 +444,12 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 
 	tun.netlinkSock, err = createNetlinkSocket()
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 	tun.netlinkCancel, err = rwcancel.NewRWCancel(tun.netlinkSock)
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 

tun/tun_openbsd.go

@@ -29,7 +29,7 @@ const _TUNSIFMODE = 0x8004745d
 
 type nativeTun struct {
 	name        string
-	fd          *os.File
+	tunFile     *os.File
 	rwcancel    *rwcancel.RWCancel
 	events      chan TUNEvent
 	errors      chan error
@@ -144,14 +144,14 @@ func CreateTUN(name string, mtu int) (TUNDevice, error) {
 func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 
 	tun := &nativeTun{
-		fd:     file,
+		tunFile: file,
-		events: make(chan TUNEvent, 10),
+		events:  make(chan TUNEvent, 10),
-		errors: make(chan error, 1),
+		errors:  make(chan error, 1),
 	}
 
 	name, err := tun.Name()
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
@@ -163,19 +163,19 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 		return iface.Index, nil
 	}()
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
 	tun.rwcancel, err = rwcancel.NewRWCancel(int(file.Fd()))
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
 	tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
 	if err != nil {
-		tun.fd.Close()
+		tun.tunFile.Close()
 		return nil, err
 	}
 
@@ -191,7 +191,7 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 }
 
 func (tun *nativeTun) Name() (string, error) {
-	gostat, err := tun.fd.Stat()
+	gostat, err := tun.tunFile.Stat()
 	if err != nil {
 		tun.name = ""
 		return "", err
@@ -202,7 +202,7 @@ func (tun *nativeTun) Name() (string, error) {
 }
 
 func (tun *nativeTun) File() *os.File {
-	return tun.fd
+	return tun.tunFile
 }
 
 func (tun *nativeTun) Events() chan TUNEvent {
@@ -215,7 +215,7 @@ func (tun *nativeTun) doRead(buff []byte, offset int) (int, error) {
 		return 0, err
 	default:
 		buff := buff[offset-4:]
-		n, err := tun.fd.Read(buff[:])
+		n, err := tun.tunFile.Read(buff[:])
 		if n < 4 {
 			return 0, err
 		}
@@ -255,13 +255,13 @@ func (tun *nativeTun) Write(buff []byte, offset int) (int, error) {
 
 	// write
 
-	return tun.fd.Write(buff)
+	return tun.tunFile.Write(buff)
 }
 
 func (tun *nativeTun) Close() error {
 	var err3 error
 	err1 := tun.rwcancel.Cancel()
-	err2 := tun.fd.Close()
+	err2 := tun.tunFile.Close()
 	if tun.routeSocket != -1 {
 		unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)
 		err3 = unix.Close(tun.routeSocket)