tun_darwin (#163)
- Remove water and replace with syscalls for tun setup - Support named interfaces - Set up routes with syscalls instead of os/exec Co-authored-by: Wade Simmons <wade@wades.im>
This commit is contained in:
Chad Harp
GitHub
parent
7801b589b6
commit
1915fab619
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@ -37,6 +37,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
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- Darwin binaries are now universal (works on both amd64 and arm64), signed, and shipped in a notarized zip file.
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`nebula-darwin.zip` will be the only darwin release artifact. (#571)
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- Darwin uses syscalls and AF_ROUTE to configure the routing table, instead of
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using `/sbin/route`. Setting `tun.dev` is now allowed on Darwin as well, it
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must be in the format `utun[0-9]+` or it will be ignored. (#163)
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### Deprecated
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- The `preferred_ranges` option has been supported as a replacement for
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@ -148,7 +148,9 @@ punchy:
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tun:
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# When tun is disabled, a lighthouse can be started without a local tun interface (and therefore without root)
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disabled: false
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# Name of the device
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# Name of the device. If not set, a default will be chosen by the OS.
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# For macOS: if set, must be in the form `utun[0-9]+`.
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# For FreeBSD: Required to be set, must be in the form `tun[0-9]+`.
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dev: nebula1
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# Toggles forwarding of local broadcast packets, the address of which depends on the ip/mask encoded in pki.cert
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drop_local_broadcast: false
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381
tun_darwin.go
381
tun_darwin.go
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@ -7,34 +7,169 @@ import (
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"fmt"
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"io"
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"net"
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"os/exec"
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"strconv"
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"os"
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"syscall"
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"unsafe"
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"github.com/sirupsen/logrus"
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"github.com/songgao/water"
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netroute "golang.org/x/net/route"
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"golang.org/x/sys/unix"
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)
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type Tun struct {
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io.ReadWriteCloser
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Device string
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Cidr *net.IPNet
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MTU int
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DefaultMTU int
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TXQueueLen int
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UnsafeRoutes []route
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l *logrus.Logger
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*water.Interface
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// cache out buffer since we need to prepend 4 bytes for tun metadata
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out []byte
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}
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func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
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type sockaddrCtl struct {
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scLen uint8
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scFamily uint8
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ssSysaddr uint16
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scID uint32
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scUnit uint32
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scReserved [5]uint32
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}
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type ifReq struct {
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Name [16]byte
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Flags uint16
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pad [8]byte
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}
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func ioctl(a1, a2, a3 uintptr) error {
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_, _, errno := unix.Syscall(unix.SYS_IOCTL, a1, a2, a3)
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if errno != 0 {
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return errno
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}
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return nil
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}
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var sockaddrCtlSize uintptr = 32
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const (
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_SYSPROTO_CONTROL = 2 //define SYSPROTO_CONTROL 2 /* kernel control protocol */
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_AF_SYS_CONTROL = 2 //#define AF_SYS_CONTROL 2 /* corresponding sub address type */
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_PF_SYSTEM = unix.AF_SYSTEM //#define PF_SYSTEM AF_SYSTEM
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_CTLIOCGINFO = 3227799043 //#define CTLIOCGINFO _IOWR('N', 3, struct ctl_info)
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utunControlName = "com.apple.net.utun_control"
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)
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type ifreqAddr struct {
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Name [16]byte
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Addr unix.RawSockaddrInet4
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pad [8]byte
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}
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type ifreqMTU struct {
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Name [16]byte
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MTU int32
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pad [8]byte
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}
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type ifreqQLEN struct {
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Name [16]byte
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Value int32
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pad [8]byte
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}
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func newTun(l *logrus.Logger, name string, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
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if len(routes) > 0 {
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return nil, fmt.Errorf("route MTU not supported in Darwin")
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}
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// NOTE: You cannot set the deviceName under Darwin, so you must check tun.Device after calling .Activate()
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return &Tun{
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Cidr: cidr,
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MTU: defaultMTU,
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UnsafeRoutes: unsafeRoutes,
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l: l,
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}, nil
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ifIndex := -1
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if name != "" && name != "utun" {
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_, err := fmt.Sscanf(name, "utun%d", &ifIndex)
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if err != nil || ifIndex < 0 {
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// NOTE: we don't make this error so we don't break existing
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// configs that set a name before it was used.
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l.Warn("interface name must be utun[0-9]+ on Darwin, ignoring")
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ifIndex = -1
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}
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}
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fd, err := unix.Socket(_PF_SYSTEM, unix.SOCK_DGRAM, _SYSPROTO_CONTROL)
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if err != nil {
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return nil, fmt.Errorf("system socket: %v", err)
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}
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var ctlInfo = &struct {
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ctlID uint32
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ctlName [96]byte
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}{}
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copy(ctlInfo.ctlName[:], []byte(utunControlName))
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err = ioctl(uintptr(fd), uintptr(_CTLIOCGINFO), uintptr(unsafe.Pointer(ctlInfo)))
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if err != nil {
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return nil, fmt.Errorf("CTLIOCGINFO: %v", err)
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}
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sc := sockaddrCtl{
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scLen: uint8(sockaddrCtlSize),
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scFamily: unix.AF_SYSTEM,
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ssSysaddr: _AF_SYS_CONTROL,
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scID: ctlInfo.ctlID,
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scUnit: uint32(ifIndex) + 1,
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}
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_, _, errno := unix.RawSyscall(
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unix.SYS_CONNECT,
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uintptr(fd),
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uintptr(unsafe.Pointer(&sc)),
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uintptr(sockaddrCtlSize),
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)
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if errno != 0 {
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return nil, fmt.Errorf("SYS_CONNECT: %v", errno)
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}
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var ifName struct {
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name [16]byte
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}
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ifNameSize := uintptr(len(ifName.name))
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_, _, errno = syscall.Syscall6(syscall.SYS_GETSOCKOPT, uintptr(fd),
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2, // SYSPROTO_CONTROL
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2, // UTUN_OPT_IFNAME
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uintptr(unsafe.Pointer(&ifName)),
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uintptr(unsafe.Pointer(&ifNameSize)), 0)
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if errno != 0 {
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return nil, fmt.Errorf("SYS_GETSOCKOPT: %v", errno)
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}
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name = string(ifName.name[:ifNameSize-1])
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err = syscall.SetNonblock(fd, true)
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if err != nil {
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return nil, fmt.Errorf("SetNonblock: %v", err)
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}
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file := os.NewFile(uintptr(fd), "")
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tun := &Tun{
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ReadWriteCloser: file,
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Device: name,
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Cidr: cidr,
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DefaultMTU: defaultMTU,
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TXQueueLen: txQueueLen,
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UnsafeRoutes: unsafeRoutes,
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l: l,
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}
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return tun, nil
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}
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func (t *Tun) deviceBytes() (o [16]byte) {
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for i, c := range t.Device {
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o[i] = byte(c)
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}
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return
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}
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func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int) (ifce *Tun, err error) {
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@ -42,43 +177,223 @@ func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU in
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}
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func (c *Tun) Close() error {
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if c.Interface != nil {
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return c.Interface.Close()
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if c.ReadWriteCloser != nil {
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return c.ReadWriteCloser.Close()
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}
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return nil
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}
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func (c *Tun) Activate() error {
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var err error
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c.Interface, err = water.New(water.Config{
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DeviceType: water.TUN,
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})
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func (t *Tun) Activate() error {
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devName := t.deviceBytes()
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var addr, mask [4]byte
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copy(addr[:], t.Cidr.IP.To4())
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copy(mask[:], t.Cidr.Mask)
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s, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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unix.IPPROTO_IP,
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)
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if err != nil {
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return fmt.Errorf("activate failed: %v", err)
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return err
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}
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c.Device = c.Interface.Name()
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fd := uintptr(s)
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// TODO use syscalls instead of exec.Command
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if err = exec.Command("/sbin/ifconfig", c.Device, c.Cidr.String(), c.Cidr.IP.String()).Run(); err != nil {
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return fmt.Errorf("failed to run 'ifconfig': %s", err)
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ifra := ifreqAddr{
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Name: devName,
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Addr: unix.RawSockaddrInet4{
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Family: unix.AF_INET,
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Addr: addr,
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},
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}
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if err = exec.Command("/sbin/route", "-n", "add", "-net", c.Cidr.String(), "-interface", c.Device).Run(); err != nil {
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return fmt.Errorf("failed to run 'route add': %s", err)
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// Set the device ip address
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if err = ioctl(fd, unix.SIOCSIFADDR, uintptr(unsafe.Pointer(&ifra))); err != nil {
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return fmt.Errorf("failed to set tun address: %s", err)
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}
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if err = exec.Command("/sbin/ifconfig", c.Device, "mtu", strconv.Itoa(c.MTU)).Run(); err != nil {
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return fmt.Errorf("failed to run 'ifconfig': %s", err)
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// Set the device network
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ifra.Addr.Addr = mask
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if err = ioctl(fd, unix.SIOCSIFNETMASK, uintptr(unsafe.Pointer(&ifra))); err != nil {
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return fmt.Errorf("failed to set tun netmask: %s", err)
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}
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// Unsafe path routes
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for _, r := range c.UnsafeRoutes {
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if err = exec.Command("/sbin/route", "-n", "add", "-net", r.route.String(), "-interface", c.Device).Run(); err != nil {
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return fmt.Errorf("failed to run 'route add' for unsafe_route %s: %s", r.route.String(), err)
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// Set the device name
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ifrf := ifReq{Name: devName}
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if err = ioctl(fd, unix.SIOCGIFFLAGS, uintptr(unsafe.Pointer(&ifrf))); err != nil {
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return fmt.Errorf("failed to set tun device name: %s", err)
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}
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// Set the MTU on the device
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ifm := ifreqMTU{Name: devName, MTU: int32(t.DefaultMTU)}
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if err = ioctl(fd, unix.SIOCSIFMTU, uintptr(unsafe.Pointer(&ifm))); err != nil {
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return fmt.Errorf("Failed to set tun mtu: %v", err)
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}
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/*
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// Set the transmit queue length
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ifrq := ifreqQLEN{Name: devName, Value: int32(t.TXQueueLen)}
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if err = ioctl(fd, unix.SIOCSIFTXQLEN, uintptr(unsafe.Pointer(&ifrq))); err != nil {
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// If we can't set the queue length nebula will still work but it may lead to packet loss
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l.WithError(err).Error("Failed to set tun tx queue length")
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}
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*/
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// Bring up the interface
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ifrf.Flags = ifrf.Flags | unix.IFF_UP
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if err = ioctl(fd, unix.SIOCSIFFLAGS, uintptr(unsafe.Pointer(&ifrf))); err != nil {
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return fmt.Errorf("failed to bring the tun device up: %s", err)
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}
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routeSock, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
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if err != nil {
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return fmt.Errorf("unable to create AF_ROUTE socket: %v", err)
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}
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defer func() {
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unix.Shutdown(routeSock, unix.SHUT_RDWR)
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err := unix.Close(routeSock)
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if err != nil {
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t.l.WithError(err).Error("failed to close AF_ROUTE socket")
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}
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}()
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routeAddr := &netroute.Inet4Addr{}
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maskAddr := &netroute.Inet4Addr{}
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linkAddr, err := getLinkAddr(t.Device)
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if err != nil {
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return err
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}
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if linkAddr == nil {
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return fmt.Errorf("unable to discover link_addr for tun interface")
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}
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copy(routeAddr.IP[:], addr[:])
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copy(maskAddr.IP[:], mask[:])
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err = addRoute(routeSock, routeAddr, maskAddr, linkAddr)
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if err != nil {
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return err
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}
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// Run the interface
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ifrf.Flags = ifrf.Flags | unix.IFF_UP | unix.IFF_RUNNING
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if err = ioctl(fd, unix.SIOCSIFFLAGS, uintptr(unsafe.Pointer(&ifrf))); err != nil {
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return fmt.Errorf("failed to run tun device: %s", err)
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}
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// Unsafe path routes
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for _, r := range t.UnsafeRoutes {
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copy(routeAddr.IP[:], r.route.IP.To4())
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copy(maskAddr.IP[:], net.IP(r.route.Mask).To4())
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err = addRoute(routeSock, routeAddr, maskAddr, linkAddr)
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if err != nil {
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return err
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}
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// TODO how to set metric
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}
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return nil
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}
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// Get the LinkAddr for the interface of the given name
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// TODO: Is there an easier way to fetch this when we create the interface?
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// Maybe SIOCGIFINDEX? but this doesn't appear to exist in the darwin headers.
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func getLinkAddr(name string) (*netroute.LinkAddr, error) {
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rib, err := netroute.FetchRIB(unix.AF_UNSPEC, unix.NET_RT_IFLIST, 0)
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if err != nil {
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return nil, err
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}
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msgs, err := netroute.ParseRIB(unix.NET_RT_IFLIST, rib)
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if err != nil {
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return nil, err
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}
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for _, m := range msgs {
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switch m := m.(type) {
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case *netroute.InterfaceMessage:
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if m.Name == name {
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sa, ok := m.Addrs[unix.RTAX_IFP].(*netroute.LinkAddr)
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if ok {
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return sa, nil
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}
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}
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}
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}
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return nil, nil
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}
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func addRoute(sock int, addr, mask *netroute.Inet4Addr, link *netroute.LinkAddr) error {
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r := netroute.RouteMessage{
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Version: unix.RTM_VERSION,
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Type: unix.RTM_ADD,
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Flags: unix.RTF_UP,
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Seq: 1,
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Addrs: []netroute.Addr{
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unix.RTAX_DST: addr,
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unix.RTAX_GATEWAY: link,
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unix.RTAX_NETMASK: mask,
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},
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}
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data, err := r.Marshal()
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if err != nil {
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return fmt.Errorf("failed to create route.RouteMessage: %v", err)
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}
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_, err = unix.Write(sock, data[:])
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if err != nil {
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return fmt.Errorf("failed to write route.RouteMessage to socket: %v", err)
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}
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return nil
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}
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var _ io.ReadWriteCloser = (*Tun)(nil)
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func (t *Tun) Read(to []byte) (int, error) {
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buf := make([]byte, len(to)+4)
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n, err := t.ReadWriteCloser.Read(buf)
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copy(to, buf[4:])
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return n - 4, err
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}
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// Write is only valid for single threaded use
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func (t *Tun) Write(from []byte) (int, error) {
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buf := t.out
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if cap(buf) < len(from)+4 {
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buf = make([]byte, len(from)+4)
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t.out = buf
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}
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buf = buf[:len(from)+4]
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if len(from) == 0 {
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return 0, syscall.EIO
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}
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// Determine the IP Family for the NULL L2 Header
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ipVer := from[0] >> 4
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if ipVer == 4 {
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buf[3] = syscall.AF_INET
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} else if ipVer == 6 {
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buf[3] = syscall.AF_INET6
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} else {
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return 0, fmt.Errorf("Unable to determine IP version from packet")
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}
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copy(buf[4:], from)
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n, err := t.ReadWriteCloser.Write(buf)
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return n - 4, err
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}
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func (c *Tun) CidrNet() *net.IPNet {
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return c.Cidr
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}
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