fix test and revert non-test changes

ipv4_test.go

@@ -77,17 +77,11 @@ readFrame:
 }
 
 func TestCloseUnblockPendingRead(t *testing.T) {
-	var (
-		self = net.IPv4(192, 168, 150, 1)
-		mask = net.IPv4Mask(255, 255, 255, 0)
-	)
-
 	ifce, err := New(Config{DeviceType: TUN})
 	if err != nil {
 		t.Fatalf("creating TUN error: %v\n", err)
 	}
 
-	setupIfce(t, net.IPNet{IP: self, Mask: mask}, ifce.Name())
 	c := make(chan struct{})
 	go func() {
 		ifce.Read(make([]byte, 1<<16))

syscalls_linux.go

@@ -31,7 +31,7 @@ func ioctl(fd uintptr, request uintptr, argp uintptr) error {
 }
 
 func newTAP(config Config) (ifce *Interface, err error) {
-	file, err := openTun()
+	file, err := os.OpenFile("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
 		return nil, err
 	}
@@ -55,7 +55,7 @@ func newTAP(config Config) (ifce *Interface, err error) {
 }
 
 func newTUN(config Config) (ifce *Interface, err error) {
-	file, err := openTun()
+	file, err := os.OpenFile("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
 		return nil, err
 	}
@@ -107,16 +107,5 @@ func setDeviceOptions(fd uintptr, config Config) (err error) {
 	if config.Persist {
 		value = 1
 	}
-
 	return ioctl(fd, syscall.TUNSETPERSIST, uintptr(value))
 }
-
-func openTun() (*os.File, error) {
-	tunFile := "/dev/net/tun"
-	bfile, err := os.OpenFile(tunFile, os.O_RDWR, 0)
-	if err != nil {
-		return nil, err
-	}
-
-	return os.NewFile(bfile.Fd(), tunFile), nil
-}