EtherGuard-VPN/tun/tun_openbsd.go
Jason A. Donenfeld 588b9f01ae Adopt GOPATH
GOPATH is annoying, but the Go community pushing me to adopt it is even
more annoying.
2018-05-23 05:18:13 +02:00

360 lines
6.3 KiB
Go

/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2017-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
package tun
import (
"git.zx2c4.com/wireguard-go/rwcancel"
"errors"
"fmt"
"golang.org/x/net/ipv6"
"golang.org/x/sys/unix"
"io/ioutil"
"net"
"os"
"syscall"
"unsafe"
)
// 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
fd *os.File
rwcancel *rwcancel.RWCancel
events chan TUNEvent
errors chan error
routeSocket int
}
func (tun *nativeTun) routineRouteListener(tunIfindex int) {
var (
statusUp bool
statusMTU int
)
defer close(tun.events)
data := make([]byte, os.Getpagesize())
for {
n, err := unix.Read(tun.routeSocket, data)
if err != nil {
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
}
iface, err := net.InterfaceByIndex(ifindex)
if err != nil {
tun.errors <- err
return
}
// Up / Down event
up := (iface.Flags & net.FlagUp) != 0
if up != statusUp && up {
tun.events <- TUNEventUp
}
if up != statusUp && !up {
tun.events <- TUNEventDown
}
statusUp = up
// MTU changes
if iface.MTU != statusMTU {
tun.events <- TUNEventMTUUpdate
}
statusMTU = iface.MTU
}
}
func errorIsEBUSY(err error) bool {
if pe, ok := err.(*os.PathError); ok {
if errno, ok := pe.Err.(syscall.Errno); ok && errno == syscall.EBUSY {
return true
}
}
if errno, ok := err.(syscall.Errno); ok && errno == syscall.EBUSY {
return true
}
return false
}
func CreateTUN(name string, mtu int) (TUNDevice, 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
}
// Set TUN iface to broadcast mode
ifmodemode := unix.IFF_BROADCAST
_, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(tunfile.Fd()),
uintptr(_TUNSIFMODE),
uintptr(unsafe.Pointer(&ifmodemode)),
)
if errno != 0 {
return nil, fmt.Errorf("error %s", errno.Error())
}
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) (TUNDevice, error) {
tun := &nativeTun{
fd: file,
events: make(chan TUNEvent, 10),
errors: make(chan error, 1),
}
name, err := tun.Name()
if err != nil {
tun.fd.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.fd.Close()
return nil, err
}
tun.rwcancel, err = rwcancel.NewRWCancel(int(file.Fd()))
if err != nil {
tun.fd.Close()
return nil, err
}
tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
if err != nil {
tun.fd.Close()
return nil, err
}
go tun.routineRouteListener(tunIfindex)
err = tun.setMTU(mtu)
if err != nil {
tun.Close()
return nil, err
}
return tun, nil
}
func (tun *nativeTun) Name() (string, error) {
gostat, err := tun.fd.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.fd
}
func (tun *nativeTun) Events() chan TUNEvent {
return tun.events
}
func (tun *nativeTun) doRead(buff []byte, offset int) (int, error) {
select {
case err := <-tun.errors:
return 0, err
default:
buff := buff[offset-4:]
n, err := tun.fd.Read(buff[:])
if n < 4 {
return 0, err
}
return n - 4, err
}
}
func (tun *nativeTun) Read(buff []byte, offset int) (int, error) {
for {
n, err := tun.doRead(buff, offset)
if err == nil || !rwcancel.ErrorIsEAGAIN(err) {
return n, err
}
if !tun.rwcancel.ReadyRead() {
return 0, errors.New("tun device closed")
}
}
}
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.fd.Write(buff)
}
func (tun *nativeTun) Close() error {
var err3 error
err1 := tun.rwcancel.Cancel()
err2 := tun.fd.Close()
if tun.routeSocket != -1 {
unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)
err3 = unix.Close(tun.routeSocket)
tun.routeSocket = -1
} else if tun.events != nil {
close(tun.events)
}
if err1 != nil {
return err1
}
if err2 != nil {
return err2
}
return err3
}
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
}