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.

1 files changed, 16 insertions, 14 deletions

diff --git a/tun/tun_darwin.go b/tun/tun_darwin.go
index 24d2319..a4e2e9a 100644
--- a/tun/tun_darwin.go
+++ b/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,
-		events: make(chan TUNEvent, 10),
-		errors: make(chan error, 1),
+		tunFile: file,
+		fd:      file.Fd(),
+		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)