Add support for NetBSD tun(4) interface

netbsd-dev-clean
snow 2 years ago committed by snow flurry
parent 3b95c81cc1
commit c644c61a8e
  1. 2
      ipc/uapi_bsd.go
  2. 2
      ipc/uapi_unix.go
  3. 374
      tun/tun_netbsd.go

@ -1,4 +1,4 @@
//go:build darwin || freebsd || openbsd
//go:build darwin || freebsd || openbsd || netbsd
/* SPDX-License-Identifier: MIT
*

@ -1,4 +1,4 @@
//go:build linux || darwin || freebsd || openbsd
//go:build linux || darwin || freebsd || openbsd || netbsd
/* SPDX-License-Identifier: MIT
*

@ -0,0 +1,374 @@
/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2020 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 (
_TUNGIFHEAD = 0x40047441
_TUNSIFMODE = 0x80047458
_TUNSIFHEAD = 0x80047442
)
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)
// Enable ifhead mode, otherwise tun will complain if it gets a non-AF_INET packet
ifheadmode := 1
var errno syscall.Errno
_, _, errno = unix.Syscall(
unix.SYS_IOCTL,
tunfile.Fd(),
uintptr(_TUNSIFHEAD),
uintptr(unsafe.Pointer(&ifheadmode)),
)
if errno != 0 {
tunfile.Close()
return nil, fmt.Errorf("Unable to put into IFHEAD mode: %v", errno)
}
_, _, errno = unix.Syscall(
unix.SYS_IOCTL,
tunfile.Fd(),
uintptr(_TUNGIFHEAD),
uintptr(unsafe.Pointer(&ifheadmode)),
)
if errno != 0 || ifheadmode != 1 {
tunfile.Close()
return nil, fmt.Errorf("Unable to validate IFHEAD mode: %v (ifheadmode = %d)", errno, ifheadmode)
}
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:]
// buff := buff[offset:]
n, err := tun.tunFile.Read(buff[:])
if n < 4 {
return 0, err
}
return n - 4, err
// return n, 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
}
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