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wintun: Use native Win32 API for I/O

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Signed-off-by: Simon Rozman <simon@rozman.si>
This commit is contained in:
Simon Rozman 2019-03-20 21:45:40 +01:00
parent 2c51d6af48
commit 91b4e909bb
5 changed files with 174 additions and 39 deletions
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8
tun/mksyscall.go Normal file
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@ -0,0 +1,8 @@
/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
package tun
//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output ztun_windows.go tun_windows.go

13
tun/tun.go
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@ -6,7 +6,6 @@
package tun
import (
"fmt"
"os"
)
@ -27,15 +26,3 @@ type TUNDevice interface {
Events() chan TUNEvent // returns a constant channel of events related to the device
Close() error // stops the device and closes the event channel
}
func (tun *NativeTun) operateOnFd(fn func(fd uintptr)) {
sysconn, err := tun.tunFile.SyscallConn()
if err != nil {
tun.errors <- fmt.Errorf("unable to find sysconn for tunfile: %s", err.Error())
return
}
err = sysconn.Control(fn)
if err != nil {
tun.errors <- fmt.Errorf("unable to control sysconn for tunfile: %s", err.Error())
}
}

24
tun/tun_default.go Normal file
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@ -0,0 +1,24 @@
// +build !windows
/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
*/
package tun
import (
"fmt"
)
func (tun *NativeTun) operateOnFd(fn func(fd uintptr)) {
sysconn, err := tun.tunFile.SyscallConn()
if err != nil {
tun.errors <- fmt.Errorf("unable to find sysconn for tunfile: %s", err.Error())
return
}
err = sysconn.Control(fn)
if err != nil {
tun.errors <- fmt.Errorf("unable to control sysconn for tunfile: %s", err.Error())
}
}

95
tun/tun_windows.go
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@ -9,6 +9,8 @@ import (
"errors"
"os"
"sync"
"syscall"
"time"
"unsafe"
"golang.org/x/sys/windows"
@ -20,6 +22,8 @@ const (
packetExchangeAlignment uint32 = 16 // Number of bytes packets are aligned to in exchange buffers
packetSizeMax uint32 = 0xf000 - packetExchangeAlignment // Maximum packet size
packetExchangeSize uint32 = 0x100000 // Exchange buffer size (defaults to 1MiB)
retryRate = 4 // Number of retries per second to reopen device pipe
retryTimeout = 5 // Number of seconds to tolerate adapter unavailable
)
type exchgBufRead struct {
@ -36,9 +40,10 @@ type exchgBufWrite struct {
type NativeTun struct {
wt *wintun.Wintun
tunName string
tunFile *os.File
tunName *uint16
tunFile windows.Handle
tunLock sync.Mutex
close bool
rdBuff *exchgBufRead
wrBuff *exchgBufWrite
events chan TUNEvent
@ -46,6 +51,8 @@ type NativeTun struct {
forcedMtu int
}
//sys getOverlappedResult(handle windows.Handle, overlapped *windows.Overlapped, done *uint32, wait bool) (err error) = kernel32.GetOverlappedResult
func packetAlign(size uint32) uint32 {
return (size + (packetExchangeAlignment - 1)) &^ (packetExchangeAlignment - 1)
}
@ -83,9 +90,16 @@ func CreateTUN(ifname string) (TUNDevice, error) {
return nil, errors.New("Flushing interface failed: " + err.Error())
}
tunNameUTF16, err := windows.UTF16PtrFromString(wt.DataFileName())
if err != nil {
wt.DeleteInterface(0)
return nil, err
}
return &NativeTun{
wt: wt,
tunName: wt.DataFileName(),
tunName: tunNameUTF16,
tunFile: windows.InvalidHandle,
rdBuff: &exchgBufRead{},
wrBuff: &exchgBufWrite{},
events: make(chan TUNEvent, 10),
@ -94,42 +108,67 @@ func CreateTUN(ifname string) (TUNDevice, error) {
}, nil
}
func (tun *NativeTun) openTUN() {
func (tun *NativeTun) openTUN() error {
retries := retryTimeout * retryRate
for {
file, err := os.OpenFile(tun.tunName, os.O_RDWR, 0)
if tun.close {
return errors.New("Cancelled")
}
file, err := windows.CreateFile(tun.tunName, windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil, windows.OPEN_EXISTING, windows.FILE_ATTRIBUTE_NORMAL|windows.FILE_FLAG_OVERLAPPED|0x20000000 /*windows.FILE_FLAG_NO_BUFFERING*/, 0)
if err != nil {
if retries > 0 {
time.Sleep(time.Second / retryRate)
retries--
continue
}
return err
}
tun.tunFile = file
return nil
}
}
func (tun *NativeTun) closeTUN() (err error) {
if tun.tunFile != nil {
if tun.tunFile != windows.InvalidHandle {
tun.tunLock.Lock()
defer tun.tunLock.Unlock()
if tun.tunFile == nil {
if tun.tunFile == windows.InvalidHandle {
return
}
t := tun.tunFile
tun.tunFile = nil
err = t.Close()
tun.tunFile = windows.InvalidHandle
err = windows.CloseHandle(t)
}
return
}
func (tun *NativeTun) getTUN() (*os.File, error) {
if tun.tunFile == nil {
func (tun *NativeTun) getTUN() (windows.Handle, error) {
if tun.tunFile == windows.InvalidHandle {
tun.tunLock.Lock()
defer tun.tunLock.Unlock()
if tun.tunFile != nil {
if tun.tunFile != windows.InvalidHandle {
return tun.tunFile, nil
}
tun.openTUN()
err := tun.openTUN()
if err != nil {
return windows.InvalidHandle, err
}
}
return tun.tunFile, nil
}
func (tun *NativeTun) isIOCancelled(err error) bool {
// Read&WriteFile() return the same ERROR_OPERATION_ABORTED if we close the handle
// or the TUN device is put down. We need a "close" flag to distinguish.
en, ok := err.(syscall.Errno)
if tun.close && ok && en == windows.ERROR_OPERATION_ABORTED {
return true
}
return false
}
func (tun *NativeTun) Name() (string, error) {
return tun.wt.GetInterfaceName()
}
@ -143,6 +182,7 @@ func (tun *NativeTun) Events() chan TUNEvent {
}
func (tun *NativeTun) Close() error {
tun.close = true
err1 := tun.closeTUN()
if tun.events != nil {
@ -199,16 +239,22 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
}
// Fill queue.
n, err := file.Read(tun.rdBuff.data[:])
var n uint32
overlapped := &windows.Overlapped{}
err = windows.ReadFile(file, tun.rdBuff.data[:], &n, overlapped)
if err != nil {
if pe, ok := err.(*os.PathError); ok && pe.Err == os.ErrClosed {
if en, ok := err.(syscall.Errno); ok && en == windows.ERROR_IO_PENDING {
err = getOverlappedResult(file, overlapped, &n, true)
}
if err != nil {
tun.rdBuff.avail = 0
if tun.isIOCancelled(err) {
return 0, err
}
// TUN interface stopped, failed, etc. Retry.
tun.rdBuff.avail = 0
tun.closeTUN()
continue
}
}
tun.rdBuff.offset = 0
tun.rdBuff.avail = uint32(n)
}
@ -224,14 +270,23 @@ func (tun *NativeTun) flush() error {
}
// Flush write buffer.
_, err = file.Write(tun.wrBuff.data[:tun.wrBuff.offset])
var n uint32
overlapped := &windows.Overlapped{}
err = windows.WriteFile(file, tun.wrBuff.data[:tun.wrBuff.offset], &n, overlapped)
tun.wrBuff.packetNum = 0
tun.wrBuff.offset = 0
if err != nil {
// TUN interface stopped, failed, etc. Drop.
tun.closeTUN()
if en, ok := err.(syscall.Errno); ok && en == windows.ERROR_IO_PENDING {
err = getOverlappedResult(file, overlapped, &n, true)
}
if err != nil {
if tun.isIOCancelled(err) {
return err
}
tun.closeTUN()
return nil
}
}
return nil
}

61
tun/ztun_windows.go Normal file
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@ -0,0 +1,61 @@
// Code generated by 'go generate'; DO NOT EDIT.
package tun
import (
"syscall"
"unsafe"
"golang.org/x/sys/windows"
)
var _ unsafe.Pointer
// Do the interface allocations only once for common
// Errno values.
const (
errnoERROR_IO_PENDING = 997
)
var (
errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
)
// errnoErr returns common boxed Errno values, to prevent
// allocations at runtime.
func errnoErr(e syscall.Errno) error {
switch e {
case 0:
return nil
case errnoERROR_IO_PENDING:
return errERROR_IO_PENDING
}
// TODO: add more here, after collecting data on the common
// error values see on Windows. (perhaps when running
// all.bat?)
return e
}
var (
modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
procGetOverlappedResult = modkernel32.NewProc("GetOverlappedResult")
)
func getOverlappedResult(handle windows.Handle, overlapped *windows.Overlapped, done *uint32, wait bool) (err error) {
var _p0 uint32
if wait {
_p0 = 1
} else {
_p0 = 0
}
r1, _, e1 := syscall.Syscall6(procGetOverlappedResult.Addr(), 4, uintptr(handle), uintptr(unsafe.Pointer(overlapped)), uintptr(unsafe.Pointer(done)), uintptr(_p0), 0, 0)
if r1 == 0 {
if e1 != 0 {
err = errnoErr(e1)
} else {
err = syscall.EINVAL
}
}
return
}