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net/tstun: use unix.Ifreq type for Linux TAP interface configuration

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Signed-off-by: Matt Layher <mdlayher@gmail.com>
This commit is contained in:
Matt Layher
2021-08-09 14:08:37 -04:00
committed by Brad Fitzpatrick
parent 6da6d47a83
commit 8ab44b339e
4 changed files with 28 additions and 23 deletions
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42
net/tstun/tap_linux.go
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@@ -9,10 +9,9 @@ import (
"net"
"os"
"os/exec"
"syscall"
"unsafe"
"github.com/insomniacslk/dhcp/dhcpv4"
"golang.org/x/sys/unix"
"golang.zx2c4.com/wireguard/tun"
"inet.af/netaddr"
"inet.af/netstack/tcpip"
@@ -32,25 +31,30 @@ var ourMAC = net.HardwareAddr{0x30, 0x2D, 0x66, 0xEC, 0x7A, 0x93}
func init() { createTAP = createTAPLinux }
func createTAPLinux(tapName, bridgeName string) (dev tun.Device, err error) {
fd, err := syscall.Open("/dev/net/tun", syscall.O_RDWR, 0)
func createTAPLinux(tapName, bridgeName string) (tun.Device, error) {
fd, err := unix.Open("/dev/net/tun", unix.O_RDWR, 0)
if err != nil {
return nil, err
}
var ifr struct {
name [16]byte
flags uint16
_ [22]byte
dev, err := openDevice(fd, tapName, bridgeName)
if err != nil {
unix.Close(fd)
return nil, err
}
copy(ifr.name[:], tapName)
ifr.flags = syscall.IFF_TAP | syscall.IFF_NO_PI
_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.TUNSETIFF, uintptr(unsafe.Pointer(&ifr)))
if errno != 0 {
syscall.Close(fd)
return nil, errno
return dev, nil
}
func openDevice(fd int, tapName, bridgeName string) (tun.Device, error) {
ifr, err := unix.NewIfreq(tapName)
if err != nil {
return nil, err
}
if err = syscall.SetNonblock(fd, true); err != nil {
syscall.Close(fd)
// Flags are stored as a uint16 in the ifreq union.
ifr.SetUint16(unix.IFF_TAP | unix.IFF_NO_PI)
if err := unix.IoctlIfreq(fd, unix.TUNSETIFF, ifr); err != nil {
return nil, err
}
@@ -62,11 +66,13 @@ func createTAPLinux(tapName, bridgeName string) (dev tun.Device, err error) {
return nil, err
}
}
dev, _, err = tun.CreateUnmonitoredTUNFromFD(fd) // TODO: MTU
// Also sets non-blocking I/O on fd when creating tun.Device.
dev, _, err := tun.CreateUnmonitoredTUNFromFD(fd) // TODO: MTU
if err != nil {
syscall.Close(fd)
return nil, err
}
return dev, nil
}