tun: windows: get rid of retry logic
Things work fine on Windows 8.
This commit is contained in:
Jason A. Donenfeld
parent
1b550f6583
commit
3341e2d444
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@ -9,7 +9,6 @@ import (
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"errors"
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"fmt"
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"os"
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"sync"
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"sync/atomic"
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"time"
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"unsafe"
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@ -21,14 +20,10 @@ import (
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const (
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packetAlignment uint32 = 4 // Number of bytes packets are aligned to in rings
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packetSizeMax uint32 = 0xffff // Maximum packet size
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packetCapacity uint32 = 0x800000 // Ring capacity, 8MiB
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packetTrailingSize uint32 = uint32(unsafe.Sizeof(packetHeader{})) + ((packetSizeMax + (packetAlignment - 1)) &^ (packetAlignment - 1)) - packetAlignment
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ioctlRegisterRings uint32 = (51820 << 16) | (0x970 << 2) | 0 /*METHOD_BUFFERED*/ | (0x3 /*FILE_READ_DATA | FILE_WRITE_DATA*/ << 14)
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retryRate = 4 // Number of retries per second to reopen device pipe
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retryTimeout = 30 // Number of seconds to tolerate adapter unavailable
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packetSizeMax = 0xffff // Maximum packet size
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packetCapacity = 0x800000 // Ring capacity, 8MiB
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packetTrailingSize = uint32(unsafe.Sizeof(packetHeader{})) + ((packetSizeMax + (packetAlignment - 1)) &^ (packetAlignment - 1)) - packetAlignment
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ioctlRegisterRings = (51820 << 16) | (0x970 << 2) | 0 /*METHOD_BUFFERED*/ | (0x3 /*FILE_READ_DATA | FILE_WRITE_DATA*/ << 14)
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)
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type packetHeader struct {
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@ -57,8 +52,7 @@ type ringDescriptor struct {
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type NativeTun struct {
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wt *wintun.Wintun
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tunDev windows.Handle
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tunLock sync.Mutex
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handle windows.Handle
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close bool
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rings ringDescriptor
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events chan Event
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@ -70,15 +64,6 @@ func packetAlign(size uint32) uint32 {
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return (size + (packetAlignment - 1)) &^ (packetAlignment - 1)
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}
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var shouldRetryOpen = windows.RtlGetVersion().MajorVersion < 10
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func maybeRetry(x int) int {
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if shouldRetryOpen {
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return x
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}
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return 0
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}
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//
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// CreateTUN creates a Wintun adapter with the given name. Should a Wintun
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// adapter with the same name exist, it is reused.
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@ -119,7 +104,7 @@ func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID) (Dev
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tun := &NativeTun{
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wt: wt,
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tunDev: windows.InvalidHandle,
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handle: windows.InvalidHandle,
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events: make(chan Event, 10),
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errors: make(chan error, 1),
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forcedMTU: 1500,
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@ -129,7 +114,7 @@ func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID) (Dev
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tun.rings.send.ring = &ring{}
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tun.rings.send.tailMoved, err = windows.CreateEvent(nil, 0, 0, nil)
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if err != nil {
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wt.DeleteInterface()
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tun.Close()
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return nil, fmt.Errorf("Error creating event: %v", err)
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}
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@ -137,100 +122,25 @@ func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID) (Dev
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tun.rings.receive.ring = &ring{}
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tun.rings.receive.tailMoved, err = windows.CreateEvent(nil, 0, 0, nil)
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if err != nil {
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windows.CloseHandle(tun.rings.send.tailMoved)
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wt.DeleteInterface()
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tun.Close()
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return nil, fmt.Errorf("Error creating event: %v", err)
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}
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_, err = tun.getTUN()
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tun.handle, err = tun.wt.AdapterHandle()
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if err != nil {
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windows.CloseHandle(tun.rings.send.tailMoved)
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windows.CloseHandle(tun.rings.receive.tailMoved)
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tun.closeTUN()
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wt.DeleteInterface()
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tun.Close()
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return nil, err
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}
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var bytesReturned uint32
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err = windows.DeviceIoControl(tun.handle, ioctlRegisterRings, (*byte)(unsafe.Pointer(&tun.rings)), uint32(unsafe.Sizeof(tun.rings)), nil, 0, &bytesReturned, nil)
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if err != nil {
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tun.Close()
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return nil, fmt.Errorf("Error registering rings: %v", err)
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}
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return tun, nil
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}
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func (tun *NativeTun) openTUN() error {
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filename, err := tun.wt.NdisFileName()
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if err != nil {
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return err
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}
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retries := maybeRetry(retryTimeout * retryRate)
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if tun.close {
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return os.ErrClosed
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}
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name, err := windows.UTF16PtrFromString(filename)
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if err != nil {
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return err
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}
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for tun.tunDev == windows.InvalidHandle {
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tun.tunDev, err = windows.CreateFile(name, windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil, windows.OPEN_EXISTING, 0, 0)
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if err != nil {
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if retries > 0 && !tun.close {
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time.Sleep(time.Second / retryRate)
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retries--
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continue
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}
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return err
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}
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atomic.StoreUint32(&tun.rings.send.ring.head, 0)
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atomic.StoreUint32(&tun.rings.send.ring.tail, 0)
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atomic.StoreInt32(&tun.rings.send.ring.alertable, 0)
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atomic.StoreUint32(&tun.rings.receive.ring.head, 0)
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atomic.StoreUint32(&tun.rings.receive.ring.tail, 0)
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atomic.StoreInt32(&tun.rings.receive.ring.alertable, 0)
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var bytesReturned uint32
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err = windows.DeviceIoControl(tun.tunDev, ioctlRegisterRings, (*byte)(unsafe.Pointer(&tun.rings)), uint32(unsafe.Sizeof(tun.rings)), nil, 0, &bytesReturned, nil)
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if err != nil {
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return fmt.Errorf("Error registering rings: %v", err)
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}
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}
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return nil
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}
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func (tun *NativeTun) closeTUN() (err error) {
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for tun.tunDev != windows.InvalidHandle {
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tun.tunLock.Lock()
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if tun.tunDev == windows.InvalidHandle {
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tun.tunLock.Unlock()
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break
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}
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t := tun.tunDev
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tun.tunDev = windows.InvalidHandle
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err = windows.CloseHandle(t)
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tun.tunLock.Unlock()
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break
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}
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return
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}
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func (tun *NativeTun) getTUN() (handle windows.Handle, err error) {
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handle = tun.tunDev
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if handle == windows.InvalidHandle {
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tun.tunLock.Lock()
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if tun.tunDev != windows.InvalidHandle {
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handle = tun.tunDev
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tun.tunLock.Unlock()
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return
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}
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err = tun.openTUN()
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if err == nil {
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handle = tun.tunDev
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}
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tun.tunLock.Unlock()
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return
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}
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return
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}
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func (tun *NativeTun) Name() (string, error) {
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return tun.wt.InterfaceName()
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}
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@ -245,29 +155,22 @@ func (tun *NativeTun) Events() chan Event {
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func (tun *NativeTun) Close() error {
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tun.close = true
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windows.SetEvent(tun.rings.send.tailMoved) // wake the reader if it's sleeping
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var err, err2 error
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err = tun.closeTUN()
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if tun.events != nil {
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close(tun.events)
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if tun.rings.send.tailMoved != 0 {
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windows.SetEvent(tun.rings.send.tailMoved) // wake the reader if it's sleeping
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}
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err2 = windows.CloseHandle(tun.rings.receive.tailMoved)
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if err == nil {
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err = err2
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if tun.handle != windows.InvalidHandle {
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windows.CloseHandle(tun.handle)
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}
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err2 = windows.CloseHandle(tun.rings.send.tailMoved)
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if err == nil {
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err = err2
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if tun.rings.send.tailMoved != 0 {
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windows.CloseHandle(tun.rings.send.tailMoved)
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}
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_, err2 = tun.wt.DeleteInterface()
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if err == nil {
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err = err2
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if tun.rings.send.tailMoved != 0 {
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windows.CloseHandle(tun.rings.receive.tailMoved)
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}
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var err error
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if tun.wt != nil {
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_, err = tun.wt.DeleteInterface()
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}
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return err
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}
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@ -286,74 +189,60 @@ func procyield(cycles uint32)
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// Note: Read() and Write() assume the caller comes only from a single thread; there's no locking.
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func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
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retry:
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select {
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case err := <-tun.errors:
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return 0, err
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default:
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}
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retries := maybeRetry(1000)
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top:
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for !tun.close {
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_, err := tun.getTUN()
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if err != nil {
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return 0, err
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}
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buffHead := atomic.LoadUint32(&tun.rings.send.ring.head)
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if buffHead >= packetCapacity {
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return 0, errors.New("send ring head out of bounds")
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}
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start := time.Now()
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var buffTail uint32
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for {
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buffTail = atomic.LoadUint32(&tun.rings.send.ring.tail)
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if buffHead != buffTail {
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break
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}
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if tun.close {
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return 0, os.ErrClosed
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}
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if time.Since(start) >= time.Millisecond*50 {
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windows.WaitForSingleObject(tun.rings.send.tailMoved, windows.INFINITE)
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continue top
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}
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procyield(1)
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}
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if buffTail >= packetCapacity {
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if retries > 0 {
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tun.closeTUN()
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time.Sleep(time.Millisecond * 2)
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retries--
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continue
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}
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return 0, errors.New("send ring tail out of bounds")
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}
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retries = maybeRetry(1000)
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buffContent := tun.rings.send.ring.wrap(buffTail - buffHead)
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if buffContent < uint32(unsafe.Sizeof(packetHeader{})) {
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return 0, errors.New("incomplete packet header in send ring")
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}
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packet := (*packet)(unsafe.Pointer(&tun.rings.send.ring.data[buffHead]))
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if packet.size > packetSizeMax {
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return 0, errors.New("packet too big in send ring")
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}
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alignedPacketSize := packetAlign(uint32(unsafe.Sizeof(packetHeader{})) + packet.size)
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if alignedPacketSize > buffContent {
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return 0, errors.New("incomplete packet in send ring")
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}
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copy(buff[offset:], packet.data[:packet.size])
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buffHead = tun.rings.send.ring.wrap(buffHead + alignedPacketSize)
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atomic.StoreUint32(&tun.rings.send.ring.head, buffHead)
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return int(packet.size), nil
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if tun.close {
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return 0, os.ErrClosed
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}
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return 0, os.ErrClosed
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buffHead := atomic.LoadUint32(&tun.rings.send.ring.head)
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if buffHead >= packetCapacity {
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return 0, os.ErrClosed
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}
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start := time.Now()
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var buffTail uint32
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for {
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buffTail = atomic.LoadUint32(&tun.rings.send.ring.tail)
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if buffHead != buffTail {
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break
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}
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if tun.close {
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return 0, os.ErrClosed
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}
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if time.Since(start) >= time.Millisecond*50 {
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windows.WaitForSingleObject(tun.rings.send.tailMoved, windows.INFINITE)
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goto retry
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}
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procyield(1)
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}
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if buffTail >= packetCapacity {
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return 0, os.ErrClosed
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}
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buffContent := tun.rings.send.ring.wrap(buffTail - buffHead)
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if buffContent < uint32(unsafe.Sizeof(packetHeader{})) {
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return 0, errors.New("incomplete packet header in send ring")
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}
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packet := (*packet)(unsafe.Pointer(&tun.rings.send.ring.data[buffHead]))
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if packet.size > packetSizeMax {
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return 0, errors.New("packet too big in send ring")
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}
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alignedPacketSize := packetAlign(uint32(unsafe.Sizeof(packetHeader{})) + packet.size)
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if alignedPacketSize > buffContent {
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return 0, errors.New("incomplete packet in send ring")
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}
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copy(buff[offset:], packet.data[:packet.size])
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buffHead = tun.rings.send.ring.wrap(buffHead + alignedPacketSize)
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atomic.StoreUint32(&tun.rings.send.ring.head, buffHead)
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return int(packet.size), nil
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}
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func (tun *NativeTun) Flush() error {
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@ -361,47 +250,36 @@ func (tun *NativeTun) Flush() error {
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}
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func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
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retries := maybeRetry(1000)
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for {
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_, err := tun.getTUN()
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if err != nil {
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return 0, err
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}
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packetSize := uint32(len(buff) - offset)
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alignedPacketSize := packetAlign(uint32(unsafe.Sizeof(packetHeader{})) + packetSize)
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buffHead := atomic.LoadUint32(&tun.rings.receive.ring.head)
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if buffHead >= packetCapacity {
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if retries > 0 {
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tun.closeTUN()
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time.Sleep(time.Millisecond * 2)
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retries--
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continue
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}
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return 0, errors.New("receive ring head out of bounds")
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}
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retries = maybeRetry(1000)
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buffTail := atomic.LoadUint32(&tun.rings.receive.ring.tail)
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if buffTail >= packetCapacity {
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return 0, errors.New("receive ring tail out of bounds")
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}
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buffSpace := tun.rings.receive.ring.wrap(buffHead - buffTail - packetAlignment)
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if alignedPacketSize > buffSpace {
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return 0, nil // Dropping when ring is full.
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}
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packet := (*packet)(unsafe.Pointer(&tun.rings.receive.ring.data[buffTail]))
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packet.size = packetSize
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copy(packet.data[:packetSize], buff[offset:])
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atomic.StoreUint32(&tun.rings.receive.ring.tail, tun.rings.receive.ring.wrap(buffTail+alignedPacketSize))
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if atomic.LoadInt32(&tun.rings.receive.ring.alertable) != 0 {
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windows.SetEvent(tun.rings.receive.tailMoved)
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}
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return int(packetSize), nil
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if tun.close {
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return 0, os.ErrClosed
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}
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packetSize := uint32(len(buff) - offset)
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alignedPacketSize := packetAlign(uint32(unsafe.Sizeof(packetHeader{})) + packetSize)
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buffHead := atomic.LoadUint32(&tun.rings.receive.ring.head)
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if buffHead >= packetCapacity {
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return 0, os.ErrClosed
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}
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buffTail := atomic.LoadUint32(&tun.rings.receive.ring.tail)
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if buffTail >= packetCapacity {
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return 0, os.ErrClosed
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}
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buffSpace := tun.rings.receive.ring.wrap(buffHead - buffTail - packetAlignment)
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if alignedPacketSize > buffSpace {
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return 0, nil // Dropping when ring is full.
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}
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packet := (*packet)(unsafe.Pointer(&tun.rings.receive.ring.data[buffTail]))
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packet.size = packetSize
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copy(packet.data[:packetSize], buff[offset:])
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atomic.StoreUint32(&tun.rings.receive.ring.tail, tun.rings.receive.ring.wrap(buffTail+alignedPacketSize))
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if atomic.LoadInt32(&tun.rings.receive.ring.alertable) != 0 {
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windows.SetEvent(tun.rings.receive.tailMoved)
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}
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return int(packetSize), nil
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}
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// LUID returns Windows adapter instance ID.
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@ -612,21 +612,25 @@ func (wintun *Wintun) deviceData() (setupapi.DevInfo, *setupapi.DevInfoData, err
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return 0, nil, windows.ERROR_OBJECT_NOT_FOUND
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}
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// NdisFileName returns the Wintun NDIS device object name.
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func (wintun *Wintun) NdisFileName() (string, error) {
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// AdapterHandle returns a handle to the adapter device object.
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func (wintun *Wintun) AdapterHandle() (windows.Handle, error) {
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key, err := registry.OpenKey(registry.LOCAL_MACHINE, wintun.netRegKeyName(), registry.QUERY_VALUE)
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if err != nil {
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return "", fmt.Errorf("Network-specific registry key open failed: %v", err)
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return windows.InvalidHandle, fmt.Errorf("Network-specific registry key open failed: %v", err)
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}
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defer key.Close()
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// Get the interface name.
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pnpInstanceID, err := registryEx.GetStringValue(key, "PnPInstanceId")
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if err != nil {
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return "", fmt.Errorf("PnpInstanceId registry key read failed: %v", err)
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return windows.InvalidHandle, fmt.Errorf("PnPInstanceId registry key read failed: %v", err)
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}
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mangledPnpNode := strings.ReplaceAll(fmt.Sprintf("%s\\{cac88484-7515-4c03-82e6-71a87abac361}", pnpInstanceID), "\\", "#")
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return fmt.Sprintf("\\\\.\\Global\\%s", mangledPnpNode), nil
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handle, err := windows.CreateFile(windows.StringToUTF16Ptr(fmt.Sprintf("\\\\.\\Global\\%s", mangledPnpNode)), windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil, windows.OPEN_EXISTING, 0, 0)
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if err != nil {
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return windows.InvalidHandle, fmt.Errorf("CreateFile on mangled PnPInstanceId path failed: %v", err)
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}
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return handle, nil
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}
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// GUID returns the GUID of the interface.
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