mirror of
https://github.com/KusakabeShi/EtherGuard-VPN.git
synced 2024-12-05 05:30:38 +01:00
4cd06c0925
In some cases, we operate on an already-up interface, or the user brings up the interface before we start monitoring. For those situations, we should first check if the interface is already up. This still technically races between the initial check and the start of the route loop, but fixing that is a bit ugly and probably not worth it at the moment. Reported-by: Theo Buehler <tb@theobuehler.org>
341 lines
5.8 KiB
Go
341 lines
5.8 KiB
Go
/* SPDX-License-Identifier: MIT
|
|
*
|
|
* Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
|
|
*/
|
|
|
|
package tun
|
|
|
|
import (
|
|
"fmt"
|
|
"io/ioutil"
|
|
"net"
|
|
"os"
|
|
"syscall"
|
|
"unsafe"
|
|
|
|
"golang.org/x/net/ipv6"
|
|
"golang.org/x/sys/unix"
|
|
)
|
|
|
|
// Structure for iface mtu get/set ioctls
|
|
type ifreq_mtu struct {
|
|
Name [unix.IFNAMSIZ]byte
|
|
MTU uint32
|
|
Pad0 [12]byte
|
|
}
|
|
|
|
const _TUNSIFMODE = 0x8004745d
|
|
|
|
type NativeTun struct {
|
|
name string
|
|
tunFile *os.File
|
|
events chan Event
|
|
errors chan error
|
|
routeSocket int
|
|
}
|
|
|
|
func (tun *NativeTun) routineRouteListener(tunIfindex int) {
|
|
var (
|
|
statusUp bool
|
|
statusMTU int
|
|
)
|
|
|
|
defer close(tun.events)
|
|
|
|
check := func() bool {
|
|
iface, err := net.InterfaceByIndex(tunIfindex)
|
|
if err != nil {
|
|
tun.errors <- err
|
|
return true
|
|
}
|
|
|
|
// Up / Down event
|
|
up := (iface.Flags & net.FlagUp) != 0
|
|
if up != statusUp && up {
|
|
tun.events <- EventUp
|
|
}
|
|
if up != statusUp && !up {
|
|
tun.events <- EventDown
|
|
}
|
|
statusUp = up
|
|
|
|
// MTU changes
|
|
if iface.MTU != statusMTU {
|
|
tun.events <- EventMTUUpdate
|
|
}
|
|
statusMTU = iface.MTU
|
|
return false
|
|
}
|
|
|
|
if check() {
|
|
return
|
|
}
|
|
|
|
data := make([]byte, os.Getpagesize())
|
|
for {
|
|
n, err := unix.Read(tun.routeSocket, data)
|
|
if err != nil {
|
|
if errno, ok := err.(syscall.Errno); ok && errno == syscall.EINTR {
|
|
continue
|
|
}
|
|
tun.errors <- err
|
|
return
|
|
}
|
|
|
|
if n < 8 {
|
|
continue
|
|
}
|
|
|
|
if data[3 /* type */] != unix.RTM_IFINFO {
|
|
continue
|
|
}
|
|
ifindex := int(*(*uint16)(unsafe.Pointer(&data[6 /* ifindex */])))
|
|
if ifindex != tunIfindex {
|
|
continue
|
|
}
|
|
if check() {
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
func errorIsEBUSY(err error) bool {
|
|
if pe, ok := err.(*os.PathError); ok {
|
|
err = pe.Err
|
|
}
|
|
if errno, ok := err.(syscall.Errno); ok && errno == syscall.EBUSY {
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
func CreateTUN(name string, mtu int) (Device, error) {
|
|
ifIndex := -1
|
|
if name != "tun" {
|
|
_, err := fmt.Sscanf(name, "tun%d", &ifIndex)
|
|
if err != nil || ifIndex < 0 {
|
|
return nil, fmt.Errorf("Interface name must be tun[0-9]*")
|
|
}
|
|
}
|
|
|
|
var tunfile *os.File
|
|
var err error
|
|
|
|
if ifIndex != -1 {
|
|
tunfile, err = os.OpenFile(fmt.Sprintf("/dev/tun%d", ifIndex), unix.O_RDWR, 0)
|
|
} else {
|
|
for ifIndex = 0; ifIndex < 256; ifIndex += 1 {
|
|
tunfile, err = os.OpenFile(fmt.Sprintf("/dev/tun%d", ifIndex), unix.O_RDWR, 0)
|
|
if err == nil || !errorIsEBUSY(err) {
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
tun, err := CreateTUNFromFile(tunfile, mtu)
|
|
|
|
if err == nil && name == "tun" {
|
|
fname := os.Getenv("WG_TUN_NAME_FILE")
|
|
if fname != "" {
|
|
ioutil.WriteFile(fname, []byte(tun.(*NativeTun).name+"\n"), 0400)
|
|
}
|
|
}
|
|
|
|
return tun, err
|
|
}
|
|
|
|
func CreateTUNFromFile(file *os.File, mtu int) (Device, error) {
|
|
tun := &NativeTun{
|
|
tunFile: file,
|
|
events: make(chan Event, 10),
|
|
errors: make(chan error, 1),
|
|
}
|
|
|
|
name, err := tun.Name()
|
|
if err != nil {
|
|
tun.tunFile.Close()
|
|
return nil, err
|
|
}
|
|
|
|
tunIfindex, err := func() (int, error) {
|
|
iface, err := net.InterfaceByName(name)
|
|
if err != nil {
|
|
return -1, err
|
|
}
|
|
return iface.Index, nil
|
|
}()
|
|
if err != nil {
|
|
tun.tunFile.Close()
|
|
return nil, err
|
|
}
|
|
|
|
tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
|
|
if err != nil {
|
|
tun.tunFile.Close()
|
|
return nil, err
|
|
}
|
|
|
|
go tun.routineRouteListener(tunIfindex)
|
|
|
|
currentMTU, err := tun.MTU()
|
|
if err != nil || currentMTU != mtu {
|
|
err = tun.setMTU(mtu)
|
|
if err != nil {
|
|
tun.Close()
|
|
return nil, err
|
|
}
|
|
}
|
|
|
|
return tun, nil
|
|
}
|
|
|
|
func (tun *NativeTun) Name() (string, error) {
|
|
gostat, err := tun.tunFile.Stat()
|
|
if err != nil {
|
|
tun.name = ""
|
|
return "", err
|
|
}
|
|
stat := gostat.Sys().(*syscall.Stat_t)
|
|
tun.name = fmt.Sprintf("tun%d", stat.Rdev%256)
|
|
return tun.name, nil
|
|
}
|
|
|
|
func (tun *NativeTun) File() *os.File {
|
|
return tun.tunFile
|
|
}
|
|
|
|
func (tun *NativeTun) Events() chan Event {
|
|
return tun.events
|
|
}
|
|
|
|
func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
|
|
select {
|
|
case err := <-tun.errors:
|
|
return 0, err
|
|
default:
|
|
buff := buff[offset-4:]
|
|
n, err := tun.tunFile.Read(buff[:])
|
|
if n < 4 {
|
|
return 0, err
|
|
}
|
|
return n - 4, err
|
|
}
|
|
}
|
|
|
|
func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
|
|
|
|
// reserve space for header
|
|
|
|
buff = buff[offset-4:]
|
|
|
|
// add packet information header
|
|
|
|
buff[0] = 0x00
|
|
buff[1] = 0x00
|
|
buff[2] = 0x00
|
|
|
|
if buff[4]>>4 == ipv6.Version {
|
|
buff[3] = unix.AF_INET6
|
|
} else {
|
|
buff[3] = unix.AF_INET
|
|
}
|
|
|
|
// write
|
|
|
|
return tun.tunFile.Write(buff)
|
|
}
|
|
|
|
func (tun *NativeTun) Flush() error {
|
|
// TODO: can flushing be implemented by buffering and using sendmmsg?
|
|
return nil
|
|
}
|
|
|
|
func (tun *NativeTun) Close() error {
|
|
var err2 error
|
|
err1 := tun.tunFile.Close()
|
|
if tun.routeSocket != -1 {
|
|
unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)
|
|
err2 = unix.Close(tun.routeSocket)
|
|
tun.routeSocket = -1
|
|
} else if tun.events != nil {
|
|
close(tun.events)
|
|
}
|
|
if err1 != nil {
|
|
return err1
|
|
}
|
|
return err2
|
|
}
|
|
|
|
func (tun *NativeTun) setMTU(n int) error {
|
|
// open datagram socket
|
|
|
|
var fd int
|
|
|
|
fd, err := unix.Socket(
|
|
unix.AF_INET,
|
|
unix.SOCK_DGRAM,
|
|
0,
|
|
)
|
|
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
defer unix.Close(fd)
|
|
|
|
// do ioctl call
|
|
|
|
var ifr ifreq_mtu
|
|
copy(ifr.Name[:], tun.name)
|
|
ifr.MTU = uint32(n)
|
|
|
|
_, _, errno := unix.Syscall(
|
|
unix.SYS_IOCTL,
|
|
uintptr(fd),
|
|
uintptr(unix.SIOCSIFMTU),
|
|
uintptr(unsafe.Pointer(&ifr)),
|
|
)
|
|
|
|
if errno != 0 {
|
|
return fmt.Errorf("failed to set MTU on %s", tun.name)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func (tun *NativeTun) MTU() (int, error) {
|
|
// open datagram socket
|
|
|
|
fd, err := unix.Socket(
|
|
unix.AF_INET,
|
|
unix.SOCK_DGRAM,
|
|
0,
|
|
)
|
|
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
|
|
defer unix.Close(fd)
|
|
|
|
// do ioctl call
|
|
var ifr ifreq_mtu
|
|
copy(ifr.Name[:], tun.name)
|
|
|
|
_, _, errno := unix.Syscall(
|
|
unix.SYS_IOCTL,
|
|
uintptr(fd),
|
|
uintptr(unix.SIOCGIFMTU),
|
|
uintptr(unsafe.Pointer(&ifr)),
|
|
)
|
|
if errno != 0 {
|
|
return 0, fmt.Errorf("failed to get MTU on %s", tun.name)
|
|
}
|
|
|
|
return int(*(*int32)(unsafe.Pointer(&ifr.MTU))), nil
|
|
}
|