clash/listener/tun/dev/dev_linux.go
2022-01-22 13:24:31 +08:00

349 lines
7.3 KiB
Go

//go:build linux || android
// +build linux android
package dev
import (
"bytes"
"errors"
"fmt"
"github.com/Dreamacro/clash/log"
"net/url"
"os"
"os/exec"
"strconv"
"strings"
"sync"
"syscall"
"unsafe"
"golang.org/x/sys/unix"
)
const (
cloneDevicePath = "/dev/net/tun"
ifReqSize = unix.IFNAMSIZ + 64
)
type tunLinux struct {
url string
name string
tunAddress string
autoRoute bool
tunFile *os.File
mtu int
closed bool
stopOnce sync.Once
}
// OpenTunDevice return a TunDevice according a URL
func OpenTunDevice(tunAddress string, autoRoute bool) (TunDevice, error) {
deviceURL, _ := url.Parse("dev://utun")
mtu, _ := strconv.ParseInt(deviceURL.Query().Get("mtu"), 0, 32)
t := &tunLinux{
url: deviceURL.String(),
mtu: int(mtu),
tunAddress: tunAddress,
autoRoute: autoRoute,
}
switch deviceURL.Scheme {
case "dev":
var err error
var dev TunDevice
dev, err = t.openDeviceByName(deviceURL.Host)
if err != nil {
return nil, err
}
err = t.configInterface()
if err != nil {
return nil, err
}
if autoRoute {
addRoute(tunAddress)
}
return dev, nil
case "fd":
fd, err := strconv.ParseInt(deviceURL.Host, 10, 32)
if err != nil {
return nil, err
}
var dev TunDevice
dev, err = t.openDeviceByFd(int(fd))
if err != nil {
return nil, err
}
if autoRoute {
log.Warnln("linux unsupported automatic route")
}
return dev, nil
}
return nil, fmt.Errorf("unsupported device type `%s`", deviceURL.Scheme)
}
func (t *tunLinux) Name() string {
return t.name
}
func (t *tunLinux) URL() string {
return t.url
}
func (t *tunLinux) Write(buff []byte) (int, error) {
return t.tunFile.Write(buff)
}
func (t *tunLinux) Read(buff []byte) (int, error) {
return t.tunFile.Read(buff)
}
func (t *tunLinux) IsClose() bool {
return t.closed
}
func (t *tunLinux) Close() error {
t.stopOnce.Do(func() {
t.closed = true
t.tunFile.Close()
})
return nil
}
func (t *tunLinux) MTU() (int, error) {
// Sometime, we can't read MTU by SIOCGIFMTU. Then we should return the preset MTU
if t.mtu > 0 {
return t.mtu, nil
}
mtu, err := t.getInterfaceMtu()
return int(mtu), err
}
func (t *tunLinux) openDeviceByName(name string) (TunDevice, error) {
nfd, err := unix.Open(cloneDevicePath, os.O_RDWR, 0)
if err != nil {
return nil, err
}
var ifr [ifReqSize]byte
var flags uint16 = unix.IFF_TUN | unix.IFF_NO_PI
nameBytes := []byte(name)
if len(nameBytes) >= unix.IFNAMSIZ {
return nil, errors.New("interface name too long")
}
copy(ifr[:], nameBytes)
*(*uint16)(unsafe.Pointer(&ifr[unix.IFNAMSIZ])) = flags
_, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(nfd),
uintptr(unix.TUNSETIFF),
uintptr(unsafe.Pointer(&ifr[0])),
)
if errno != 0 {
return nil, errno
}
err = unix.SetNonblock(nfd, true)
if err != nil {
return nil, err
}
// Note that the above -- open,ioctl,nonblock -- must happen prior to handing it to netpoll as below this line.
t.tunFile = os.NewFile(uintptr(nfd), cloneDevicePath)
t.name, err = t.getName()
if err != nil {
t.tunFile.Close()
return nil, err
}
return t, nil
}
func (t *tunLinux) configInterface() error {
var ifr [ifReqSize]byte
nameBytes := []byte(t.name)
if len(nameBytes) >= unix.IFNAMSIZ {
return errors.New("interface name too long")
}
copy(ifr[:], nameBytes)
fd, _, errno := syscall.Syscall(unix.SYS_SOCKET, unix.AF_INET, unix.SOCK_STREAM, 0)
if errno != 0 {
return errno
}
// set addr for tun
var ip []byte
for _, num := range strings.Split(t.tunAddress, ".") {
value, err := strconv.Atoi(num)
if err != nil {
return err
}
ip = append(ip, byte(value))
}
*(*uint16)(unsafe.Pointer(&ifr[unix.IFNAMSIZ])) = uint16(unix.AF_INET)
copy(ifr[unix.IFNAMSIZ+4:], ip)
_, _, errno = unix.Syscall(
unix.SYS_IOCTL,
fd,
uintptr(unix.SIOCSIFADDR),
uintptr(unsafe.Pointer(&ifr[0])))
if errno != 0 {
return errno
}
// set netmask for tun
netmask := []byte{255, 255, 0, 0}
copy(ifr[unix.IFNAMSIZ+4:], netmask)
_, _, errno = unix.Syscall(
unix.SYS_IOCTL,
fd,
uintptr(unix.SIOCSIFNETMASK),
uintptr(unsafe.Pointer(&ifr[0])))
if errno != 0 {
return errno
}
// interface up
_, _, errno = syscall.Syscall(unix.SYS_IOCTL, fd, uintptr(unix.SIOCSIFFLAGS), uintptr(unsafe.Pointer(&ifr[0])))
var flags = uint16(unix.IFF_UP | unix.IFF_TUN | unix.IFF_MULTICAST | unix.IFF_RUNNING | unix.IFF_NOARP)
*(*uint16)(unsafe.Pointer(&ifr[unix.IFNAMSIZ])) = flags
_, _, errno = syscall.Syscall(
unix.SYS_IOCTL,
fd,
uintptr(unix.SIOCSIFFLAGS),
uintptr(unsafe.Pointer(&ifr[0])))
if errno != 0 {
return errno
}
return nil
}
func (t *tunLinux) openDeviceByFd(fd int) (TunDevice, error) {
var ifr struct {
name [16]byte
flags uint16
_ [22]byte
}
fd, err := syscall.Dup(fd)
if err != nil {
return nil, err
}
_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.TUNGETIFF, uintptr(unsafe.Pointer(&ifr)))
if errno != 0 {
return nil, errno
}
if ifr.flags&syscall.IFF_TUN == 0 || ifr.flags&syscall.IFF_NO_PI == 0 {
return nil, errors.New("only tun device and no pi mode supported")
}
nullStr := ifr.name[:]
i := bytes.IndexByte(nullStr, 0)
if i != -1 {
nullStr = nullStr[:i]
}
t.name = string(nullStr)
t.tunFile = os.NewFile(uintptr(fd), "/dev/tun")
return t, nil
}
func (t *tunLinux) getInterfaceMtu() (uint32, error) {
fd, err := syscall.Socket(syscall.AF_UNIX, syscall.SOCK_DGRAM, 0)
if err != nil {
return 0, err
}
defer syscall.Close(fd)
var ifreq struct {
name [16]byte
mtu int32
_ [20]byte
}
copy(ifreq.name[:], t.name)
_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.SIOCGIFMTU, uintptr(unsafe.Pointer(&ifreq)))
if errno != 0 {
return 0, errno
}
return uint32(ifreq.mtu), nil
}
func (t *tunLinux) getName() (string, error) {
sysconn, err := t.tunFile.SyscallConn()
if err != nil {
return "", err
}
var ifr [ifReqSize]byte
var errno syscall.Errno
err = sysconn.Control(func(fd uintptr) {
_, _, errno = unix.Syscall(
unix.SYS_IOCTL,
fd,
uintptr(unix.TUNGETIFF),
uintptr(unsafe.Pointer(&ifr[0])),
)
})
if err != nil {
return "", errors.New("failed to get name of TUN device: " + err.Error())
}
if errno != 0 {
return "", errors.New("failed to get name of TUN device: " + errno.Error())
}
nullStr := ifr[:]
i := bytes.IndexByte(nullStr, 0)
if i != -1 {
nullStr = nullStr[:i]
}
t.name = string(nullStr)
return t.name, nil
}
// GetAutoDetectInterface get ethernet interface
func GetAutoDetectInterface() (string, error) {
cmd := exec.Command("bash", "-c", "ip route show | grep 'default via' | awk -F ' ' 'NR==1{print $5}' | xargs echo -n")
var out bytes.Buffer
cmd.Stdout = &out
err := cmd.Run()
if err != nil {
return "", err
}
return out.String(), nil
}
func addRoute(gateway string) {
cmd := exec.Command("route", "add", "default", "gw", gateway)
var stderr bytes.Buffer
cmd.Stderr = &stderr
if err := cmd.Run(); err != nil {
log.Errorln("[auto route] Failed to add system route: %s: %s , cmd: %s", err.Error(), stderr.String(), cmd.String())
}
}
func delRoute(gateway string) {
cmd := exec.Command("ip", "route", "delete", "gw")
var stderr bytes.Buffer
cmd.Stderr = &stderr
if err := cmd.Run(); err != nil {
log.Errorln("[auto route] Failed to delete system route: %s: %s , cmd: %s", err.Error(), stderr.String(), cmd.String())
}
}