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-rw-r--r--tun/tun_windows.go370
1 files changed, 184 insertions, 186 deletions
diff --git a/tun/tun_windows.go b/tun/tun_windows.go
index 4ae5cf0..49cbdad 100644
--- a/tun/tun_windows.go
+++ b/tun/tun_windows.go
@@ -8,9 +8,9 @@ package tun
import (
"errors"
"fmt"
- "io"
"os"
"sync"
+ "sync/atomic"
"time"
"unsafe"
@@ -20,39 +20,54 @@ import (
)
const (
- packetExchangeAlignment uint32 = 4 // 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 = 30 // Number of seconds to tolerate adapter unavailable
+ packetAlignment uint32 = 4 // Number of bytes packets are aligned to in rings
+ packetSizeMax uint32 = 0xffff // Maximum packet size
+ packetCapacity uint32 = 0x100000 // Ring capacity (defaults to 1MiB, must be a power of 2)
+ packetTrailingSize uint32 = uint32(unsafe.Sizeof(packetHeader{})) + ((packetSizeMax + (packetAlignment - 1)) &^ (packetAlignment - 1)) - packetAlignment
+
+ ioctlRegisterRings uint32 = (0x22 /*FILE_DEVICE_UNKNOWN*/ << 16) | (0x800 << 2) | 0 /*METHOD_BUFFERED*/ | (0x3 /*FILE_READ_DATA | FILE_WRITE_DATA*/ << 14)
+
+ retryRate = 4 // Number of retries per second to reopen device pipe
+ retryTimeout = 30 // Number of seconds to tolerate adapter unavailable
)
-type exchgBufRead struct {
- data [packetExchangeSize]byte
- offset uint32
- avail uint32
+type packetHeader struct {
+ size uint32
+}
+
+type packet struct {
+ packetHeader
+ data [packetSizeMax]byte
}
-type exchgBufWrite struct {
- data [packetExchangeSize]byte
- offset uint32
+type ring struct {
+ head uint32
+ tail uint32
+ alertable int32
+ data [packetCapacity + packetTrailingSize]byte
+}
+
+type ringDescriptor struct {
+ send, receive struct {
+ size uint32
+ ring *ring
+ tailMoved windows.Handle
+ }
}
type NativeTun struct {
- wt *wintun.Wintun
- tunFileRead *os.File
- tunFileWrite *os.File
- tunLock sync.Mutex
- close bool
- rdBuff *exchgBufRead
- wrBuff *exchgBufWrite
- events chan Event
- errors chan error
- forcedMTU int
+ wt *wintun.Wintun
+ tunDev windows.Handle
+ tunLock sync.Mutex
+ close bool
+ rings ringDescriptor
+ events chan Event
+ errors chan error
+ forcedMTU int
}
func packetAlign(size uint32) uint32 {
- return (size + (packetExchangeAlignment - 1)) &^ (packetExchangeAlignment - 1)
+ return (size + (packetAlignment - 1)) &^ (packetAlignment - 1)
}
var shouldRetryOpen = windows.RtlGetVersion().MajorVersion < 10
@@ -102,14 +117,32 @@ func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID) (Dev
return nil, fmt.Errorf("Unable to set name of Wintun interface: %v", err)
}
- return &NativeTun{
+ tun := &NativeTun{
wt: wt,
- rdBuff: &exchgBufRead{},
- wrBuff: &exchgBufWrite{},
+ tunDev: windows.InvalidHandle,
events: make(chan Event, 10),
errors: make(chan error, 1),
forcedMTU: 1500,
- }, nil
+ }
+
+ tun.rings.send.size = uint32(unsafe.Sizeof(ring{}))
+ tun.rings.send.ring = &ring{}
+ tun.rings.send.tailMoved, err = windows.CreateEvent(nil, 0, 0, nil)
+ if err != nil {
+ wt.DeleteInterface()
+ return nil, fmt.Errorf("Error creating event: %v", err)
+ }
+
+ tun.rings.receive.size = uint32(unsafe.Sizeof(ring{}))
+ tun.rings.receive.ring = &ring{}
+ tun.rings.receive.tailMoved, err = windows.CreateEvent(nil, 0, 0, nil)
+ if err != nil {
+ windows.CloseHandle(tun.rings.send.tailMoved)
+ wt.DeleteInterface()
+ return nil, fmt.Errorf("Error creating event: %v", err)
+ }
+
+ return tun, nil
}
func (tun *NativeTun) openTUN() error {
@@ -119,9 +152,12 @@ func (tun *NativeTun) openTUN() error {
}
var err error
- name := tun.wt.DataFileName()
- for tun.tunFileRead == nil {
- tun.tunFileRead, err = os.OpenFile(name, os.O_RDONLY, 0)
+ name, err := windows.UTF16PtrFromString(tun.wt.DataFileName())
+ if err != nil {
+ return err
+ }
+ for tun.tunDev == windows.InvalidHandle {
+ tun.tunDev, err = windows.CreateFile(name, windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil, windows.OPEN_EXISTING, 0, 0)
if err != nil {
if retries > 0 && !tun.close {
time.Sleep(time.Second / retryRate)
@@ -130,72 +166,51 @@ func (tun *NativeTun) openTUN() error {
}
return err
}
- }
- for tun.tunFileWrite == nil {
- tun.tunFileWrite, err = os.OpenFile(name, os.O_WRONLY, 0)
+
+ atomic.StoreUint32(&tun.rings.send.ring.head, 0)
+ atomic.StoreUint32(&tun.rings.send.ring.tail, 0)
+ atomic.StoreInt32(&tun.rings.send.ring.alertable, 0)
+ atomic.StoreUint32(&tun.rings.receive.ring.head, 0)
+ atomic.StoreUint32(&tun.rings.receive.ring.tail, 0)
+ atomic.StoreInt32(&tun.rings.receive.ring.alertable, 0)
+
+ var bytesReturned uint32
+ err = windows.DeviceIoControl(tun.tunDev, ioctlRegisterRings, (*byte)(unsafe.Pointer(&tun.rings)), uint32(unsafe.Sizeof(tun.rings)), nil, 0, &bytesReturned, nil)
if err != nil {
- if retries > 0 && !tun.close {
- time.Sleep(time.Second / retryRate)
- retries--
- continue
- }
- return err
+ return fmt.Errorf("Error registering rings: %v", err)
}
}
return nil
}
func (tun *NativeTun) closeTUN() (err error) {
- for tun.tunFileRead != nil {
- tun.tunLock.Lock()
- if tun.tunFileRead == nil {
- tun.tunLock.Unlock()
- break
- }
- t := tun.tunFileRead
- tun.tunFileRead = nil
- windows.CancelIoEx(windows.Handle(t.Fd()), nil)
- err = t.Close()
- tun.tunLock.Unlock()
- break
- }
- for tun.tunFileWrite != nil {
+ for tun.tunDev != windows.InvalidHandle {
tun.tunLock.Lock()
- if tun.tunFileWrite == nil {
+ if tun.tunDev == windows.InvalidHandle {
tun.tunLock.Unlock()
break
}
- t := tun.tunFileWrite
- tun.tunFileWrite = nil
- windows.CancelIoEx(windows.Handle(t.Fd()), nil)
- err2 := t.Close()
+ t := tun.tunDev
+ tun.tunDev = windows.InvalidHandle
+ err = windows.CloseHandle(t)
tun.tunLock.Unlock()
- if err == nil {
- err = err2
- }
break
}
return
}
-func (tun *NativeTun) getTUN() (read *os.File, write *os.File, err error) {
- read, write = tun.tunFileRead, tun.tunFileWrite
- if read == nil || write == nil {
- read, write = nil, nil
+func (tun *NativeTun) getTUN() (handle windows.Handle, err error) {
+ handle = tun.tunDev
+ if handle == windows.InvalidHandle {
tun.tunLock.Lock()
- if tun.tunFileRead != nil && tun.tunFileWrite != nil {
- read, write = tun.tunFileRead, tun.tunFileWrite
- tun.tunLock.Unlock()
- return
- }
- err = tun.closeTUN()
- if err != nil {
+ if tun.tunDev != windows.InvalidHandle {
+ handle = tun.tunDev
tun.tunLock.Unlock()
return
}
err = tun.openTUN()
if err == nil {
- read, write = tun.tunFileRead, tun.tunFileWrite
+ handle = tun.tunDev
}
tun.tunLock.Unlock()
return
@@ -217,18 +232,30 @@ func (tun *NativeTun) Events() chan Event {
func (tun *NativeTun) Close() error {
tun.close = true
- err1 := tun.closeTUN()
+ windows.SetEvent(tun.rings.send.tailMoved) // wake the reader if it's sleeping
+ var err, err2 error
+ err = tun.closeTUN()
if tun.events != nil {
close(tun.events)
}
- _, err2 := tun.wt.DeleteInterface()
- if err1 == nil {
- err1 = err2
+ err2 = windows.CloseHandle(tun.rings.receive.tailMoved)
+ if err == nil {
+ err = err2
+ }
+
+ err2 = windows.CloseHandle(tun.rings.send.tailMoved)
+ if err == nil {
+ err = err2
+ }
+
+ _, err2 = tun.wt.DeleteInterface()
+ if err == nil {
+ err = err2
}
- return err1
+ return err
}
func (tun *NativeTun) MTU() (int, error) {
@@ -240,6 +267,8 @@ func (tun *NativeTun) ForceMTU(mtu int) {
tun.forcedMTU = mtu
}
+// Note: Read() and Write() assume the caller comes only from a single thread; there's no locking.
+
func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
select {
case err := <-tun.errors:
@@ -248,142 +277,111 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
}
retries := maybeRetry(1000)
- for {
- if tun.rdBuff.offset+packetExchangeAlignment <= tun.rdBuff.avail {
- // Get packet from the exchange buffer.
- packet := tun.rdBuff.data[tun.rdBuff.offset:]
- size := *(*uint32)(unsafe.Pointer(&packet[0]))
- pSize := packetAlign(size) + packetExchangeAlignment
- if packetSizeMax < size || tun.rdBuff.avail < tun.rdBuff.offset+pSize {
- // Invalid packet size.
- tun.rdBuff.avail = 0
- continue
- }
- packet = packet[packetExchangeAlignment : packetExchangeAlignment+size]
-
- // Copy data.
- copy(buff[offset:], packet)
- tun.rdBuff.offset += pSize
- return int(size), nil
- }
-
- // Get TUN data pipe.
- file, _, err := tun.getTUN()
+ for !tun.close {
+ _, err := tun.getTUN()
if err != nil {
return 0, err
}
- n, err := file.Read(tun.rdBuff.data[:])
- if err != nil {
- tun.rdBuff.offset = 0
- tun.rdBuff.avail = 0
- pe, ok := err.(*os.PathError)
- if tun.close {
- return 0, os.ErrClosed
- }
- if retries > 0 && ok && (pe.Err == windows.ERROR_HANDLE_EOF || pe.Err == windows.ERROR_OPERATION_ABORTED) {
- retries--
+ buffHead := atomic.LoadUint32(&tun.rings.send.ring.head)
+ if buffHead >= packetCapacity {
+ return 0, errors.New("send ring head out of bounds")
+ }
+
+ buffTail := atomic.LoadUint32(&tun.rings.send.ring.tail)
+ if buffHead == buffTail {
+ windows.WaitForSingleObject(tun.rings.send.tailMoved, windows.INFINITE)
+ continue
+ }
+ if buffTail >= packetCapacity {
+ if retries > 0 {
tun.closeTUN()
time.Sleep(time.Millisecond * 2)
+ retries--
continue
}
- return 0, err
+ return 0, errors.New("send ring tail out of bounds")
}
- if n == 0 {
- if retries == 0 {
- return 0, io.ErrShortBuffer
- }
- retries--
- continue
+ retries = maybeRetry(1000)
+
+ buffContent := tun.rings.send.ring.wrap(buffTail - buffHead)
+ if buffContent < uint32(unsafe.Sizeof(packetHeader{})) {
+ return 0, errors.New("incomplete packet header in send ring")
}
- tun.rdBuff.offset = 0
- tun.rdBuff.avail = uint32(n)
+
+ packet := (*packet)(unsafe.Pointer(&tun.rings.send.ring.data[buffHead]))
+ if packet.size > packetSizeMax {
+ return 0, errors.New("packet too big in send ring")
+ }
+
+ alignedPacketSize := packetAlign(uint32(unsafe.Sizeof(packetHeader{})) + packet.size)
+ if alignedPacketSize > buffContent {
+ return 0, errors.New("incomplete packet in send ring")
+ }
+
+ copy(buff[offset:], packet.data[:packet.size])
+ buffHead = tun.rings.send.ring.wrap(buffHead + alignedPacketSize)
+ atomic.StoreUint32(&tun.rings.send.ring.head, buffHead)
+ return int(packet.size), nil
}
-}
-// Note: flush() and putTunPacket() assume the caller comes only from a single thread; there's no locking.
+ return 0, os.ErrClosed
+}
func (tun *NativeTun) Flush() error {
- if tun.wrBuff.offset == 0 {
- return nil
- }
- defer func() {
- tun.wrBuff.offset = 0
- }()
- retries := maybeRetry(1000)
+ return nil
+}
+func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
+ retries := maybeRetry(1000)
for {
- // Get TUN data pipe.
- _, file, err := tun.getTUN()
+ _, err := tun.getTUN()
if err != nil {
- return err
+ return 0, err
}
- for {
- _, err = file.Write(tun.wrBuff.data[:tun.wrBuff.offset])
- if err != nil {
- pe, ok := err.(*os.PathError)
- if tun.close {
- return os.ErrClosed
- }
- if retries > 0 && ok && pe.Err == windows.ERROR_OPERATION_ABORTED { // Adapter is paused or in low-power state.
- retries--
- time.Sleep(time.Millisecond * 2)
- continue
- }
- if retries > 0 && ok && pe.Err == windows.ERROR_HANDLE_EOF { // Adapter is going down.
- retries--
- tun.closeTUN()
- time.Sleep(time.Millisecond * 2)
- break
- }
- return err
+ packetSize := uint32(len(buff) - offset)
+ alignedPacketSize := packetAlign(uint32(unsafe.Sizeof(packetHeader{})) + packetSize)
+
+ buffHead := atomic.LoadUint32(&tun.rings.receive.ring.head)
+ if buffHead >= packetCapacity {
+ if retries > 0 {
+ tun.closeTUN()
+ time.Sleep(time.Millisecond * 2)
+ retries--
+ continue
}
- return nil
+ return 0, errors.New("receive ring head out of bounds")
}
- }
-}
-
-func (tun *NativeTun) putTunPacket(buff []byte) error {
- size := uint32(len(buff))
- if size == 0 {
- return errors.New("Empty packet")
- }
- if size > packetSizeMax {
- return errors.New("Packet too big")
- }
- pSize := packetAlign(size) + packetExchangeAlignment
+ retries = maybeRetry(1000)
- if tun.wrBuff.offset+pSize >= packetExchangeSize {
- // Exchange buffer is full -> flush first.
- err := tun.Flush()
- if err != nil {
- return err
+ buffTail := atomic.LoadUint32(&tun.rings.receive.ring.tail)
+ if buffTail >= packetCapacity {
+ return 0, errors.New("receive ring tail out of bounds")
}
- }
- // Write packet to the exchange buffer.
- packet := tun.wrBuff.data[tun.wrBuff.offset : tun.wrBuff.offset+pSize]
- *(*uint32)(unsafe.Pointer(&packet[0])) = size
- packet = packet[packetExchangeAlignment : packetExchangeAlignment+size]
- copy(packet, buff)
-
- tun.wrBuff.offset += pSize
-
- return nil
-}
+ buffSpace := tun.rings.receive.ring.wrap(buffHead - buffTail - packetAlignment)
+ if alignedPacketSize > buffSpace {
+ return 0, errors.New("receive ring full")
+ }
-func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
- err := tun.putTunPacket(buff[offset:])
- if err != nil {
- return 0, err
+ packet := (*packet)(unsafe.Pointer(&tun.rings.receive.ring.data[buffTail]))
+ packet.size = packetSize
+ copy(packet.data[:packetSize], buff[offset:])
+ atomic.StoreUint32(&tun.rings.receive.ring.tail, tun.rings.receive.ring.wrap(buffTail+alignedPacketSize))
+ if atomic.LoadInt32(&tun.rings.receive.ring.alertable) != 0 {
+ windows.SetEvent(tun.rings.receive.tailMoved)
+ }
+ return int(packetSize), nil
}
- return len(buff) - offset, nil
}
-//
// LUID returns Windows adapter instance ID.
-//
func (tun *NativeTun) LUID() uint64 {
return tun.wt.LUID()
}
+
+// wrap returns value modulo ring capacity
+func (rb *ring) wrap(value uint32) uint32 {
+ return value & (packetCapacity - 1)
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 07:00:51 +0000