391 lines
7.1 KiB
Go
391 lines
7.1 KiB
Go
/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
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*/
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package tun
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import (
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"fmt"
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"io/ioutil"
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"net"
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"os"
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"syscall"
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"time"
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"unsafe"
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"golang.org/x/net/ipv6"
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"golang.org/x/sys/unix"
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)
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const utunControlName = "com.apple.net.utun_control"
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// _CTLIOCGINFO value derived from /usr/include/sys/{kern_control,ioccom}.h
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const _CTLIOCGINFO = (0x40000000 | 0x80000000) | ((100 & 0x1fff) << 16) | uint32(byte('N'))<<8 | 3
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// sockaddr_ctl specifeid in /usr/include/sys/kern_control.h
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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 NativeTun struct {
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name string
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tunFile *os.File
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events chan Event
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errors chan error
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routeSocket int
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}
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var sockaddrCtlSize uintptr = 32
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func retryInterfaceByIndex(index int) (iface *net.Interface, err error) {
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for i := 0; i < 20; i++ {
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iface, err = net.InterfaceByIndex(index)
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if err != nil {
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if opErr, ok := err.(*net.OpError); ok {
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if syscallErr, ok := opErr.Err.(*os.SyscallError); ok && syscallErr.Err == syscall.ENOMEM {
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time.Sleep(time.Duration(i) * time.Second / 3)
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continue
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}
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}
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}
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return iface, err
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}
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return nil, err
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}
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func (tun *NativeTun) routineRouteListener(tunIfindex int) {
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var (
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statusUp bool
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statusMTU int
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)
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defer close(tun.events)
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data := make([]byte, os.Getpagesize())
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for {
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retry:
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n, err := unix.Read(tun.routeSocket, data)
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if err != nil {
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if errno, ok := err.(syscall.Errno); ok && errno == syscall.EINTR {
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goto retry
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}
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tun.errors <- err
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return
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}
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if n < 14 {
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continue
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}
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if data[3 /* type */] != unix.RTM_IFINFO {
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continue
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}
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ifindex := int(*(*uint16)(unsafe.Pointer(&data[12 /* ifindex */])))
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if ifindex != tunIfindex {
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continue
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}
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iface, err := retryInterfaceByIndex(ifindex)
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if err != nil {
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tun.errors <- err
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return
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}
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// Up / Down event
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up := (iface.Flags & net.FlagUp) != 0
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if up != statusUp && up {
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tun.events <- EventUp
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}
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if up != statusUp && !up {
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tun.events <- EventDown
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}
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statusUp = up
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// MTU changes
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if iface.MTU != statusMTU {
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tun.events <- EventMTUUpdate
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}
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statusMTU = iface.MTU
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}
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}
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func CreateTUN(name string, mtu int) (Device, error) {
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ifIndex := -1
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if 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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return nil, fmt.Errorf("Interface name must be utun[0-9]*")
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}
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}
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fd, err := unix.Socket(unix.AF_SYSTEM, unix.SOCK_DGRAM, 2)
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if err != nil {
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return nil, 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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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(fd),
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uintptr(_CTLIOCGINFO),
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uintptr(unsafe.Pointer(ctlInfo)),
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)
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if errno != 0 {
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return nil, fmt.Errorf("_CTLIOCGINFO: %v", errno)
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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: 2,
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scID: ctlInfo.ctlID,
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scUnit: uint32(ifIndex) + 1,
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}
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scPointer := unsafe.Pointer(&sc)
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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(scPointer),
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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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err = syscall.SetNonblock(fd, true)
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if err != nil {
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return nil, err
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}
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tun, err := CreateTUNFromFile(os.NewFile(uintptr(fd), ""), mtu)
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if err == nil && name == "utun" {
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fname := os.Getenv("WG_TUN_NAME_FILE")
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if fname != "" {
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ioutil.WriteFile(fname, []byte(tun.(*NativeTun).name+"\n"), 0400)
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}
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}
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return tun, err
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}
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func CreateTUNFromFile(file *os.File, mtu int) (Device, error) {
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tun := &NativeTun{
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tunFile: file,
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events: make(chan Event, 10),
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errors: make(chan error, 5),
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}
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name, err := tun.Name()
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if err != nil {
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tun.tunFile.Close()
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return nil, err
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}
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tunIfindex, err := func() (int, error) {
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iface, err := net.InterfaceByName(name)
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if err != nil {
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return -1, err
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}
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return iface.Index, nil
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}()
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if err != nil {
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tun.tunFile.Close()
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return nil, err
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}
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tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
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if err != nil {
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tun.tunFile.Close()
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return nil, err
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}
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go tun.routineRouteListener(tunIfindex)
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if mtu > 0 {
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err = tun.setMTU(mtu)
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if err != nil {
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tun.Close()
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return nil, err
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}
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}
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return tun, nil
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}
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func (tun *NativeTun) Name() (string, error) {
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var ifName struct {
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name [16]byte
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}
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ifNameSize := uintptr(16)
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var errno syscall.Errno
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tun.operateOnFd(func(fd uintptr) {
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_, _, errno = unix.Syscall6(
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unix.SYS_GETSOCKOPT,
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fd,
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2, /* #define SYSPROTO_CONTROL 2 */
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2, /* #define UTUN_OPT_IFNAME 2 */
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uintptr(unsafe.Pointer(&ifName)),
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uintptr(unsafe.Pointer(&ifNameSize)), 0)
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})
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if errno != 0 {
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return "", fmt.Errorf("SYS_GETSOCKOPT: %v", errno)
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}
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tun.name = string(ifName.name[:ifNameSize-1])
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return tun.name, nil
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}
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func (tun *NativeTun) File() *os.File {
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return tun.tunFile
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}
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func (tun *NativeTun) Events() chan Event {
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return tun.events
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}
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func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
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select {
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case err := <-tun.errors:
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return 0, err
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default:
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buff := buff[offset-4:]
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n, err := tun.tunFile.Read(buff[:])
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if n < 4 {
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return 0, err
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}
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return n - 4, err
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}
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}
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func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
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// reserve space for header
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buff = buff[offset-4:]
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// add packet information header
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buff[0] = 0x00
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buff[1] = 0x00
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buff[2] = 0x00
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if buff[4]>>4 == ipv6.Version {
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buff[3] = unix.AF_INET6
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} else {
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buff[3] = unix.AF_INET
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}
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// write
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return tun.tunFile.Write(buff)
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}
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func (tun *NativeTun) Flush() error {
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// TODO: can flushing be implemented by buffering and using sendmmsg?
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return nil
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}
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func (tun *NativeTun) Close() error {
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var err2 error
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err1 := tun.tunFile.Close()
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if tun.routeSocket != -1 {
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unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)
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err2 = unix.Close(tun.routeSocket)
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} else if tun.events != nil {
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close(tun.events)
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}
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if err1 != nil {
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return err1
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}
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return err2
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}
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func (tun *NativeTun) setMTU(n int) error {
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// open datagram socket
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var fd int
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fd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return err
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}
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defer unix.Close(fd)
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// do ioctl call
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var ifr [32]byte
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copy(ifr[:], tun.name)
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*(*uint32)(unsafe.Pointer(&ifr[unix.IFNAMSIZ])) = uint32(n)
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(fd),
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uintptr(unix.SIOCSIFMTU),
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uintptr(unsafe.Pointer(&ifr[0])),
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)
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if errno != 0 {
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return fmt.Errorf("failed to set MTU on %s", tun.name)
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}
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return nil
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}
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func (tun *NativeTun) MTU() (int, error) {
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// open datagram socket
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fd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return 0, err
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}
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defer unix.Close(fd)
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// do ioctl call
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var ifr [64]byte
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copy(ifr[:], tun.name)
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(fd),
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uintptr(unix.SIOCGIFMTU),
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uintptr(unsafe.Pointer(&ifr[0])),
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)
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if errno != 0 {
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return 0, fmt.Errorf("failed to get MTU on %s", tun.name)
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}
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return int(*(*int32)(unsafe.Pointer(&ifr[16]))), nil
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}
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