tun: windows: implement ring buffers
Signed-off-by: Simon Rozman <simon@rozman.si>
This commit is contained in:
Simon Rozman
Jason A. Donenfeld
parent
a961aacc9f
commit
2e24e7dcae
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@ -8,9 +8,9 @@ package tun
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import (
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"errors"
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"fmt"
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"io"
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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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@ -20,39 +20,54 @@ import (
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)
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const (
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packetExchangeAlignment uint32 = 4 // Number of bytes packets are aligned to in exchange buffers
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packetSizeMax uint32 = 0xf000 - packetExchangeAlignment // Maximum packet size
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packetExchangeSize uint32 = 0x100000 // Exchange buffer size (defaults to 1MiB)
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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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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 = 0x100000 // Ring capacity (defaults to 1MiB, must be a power of 2)
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packetTrailingSize uint32 = uint32(unsafe.Sizeof(packetHeader{})) + ((packetSizeMax + (packetAlignment - 1)) &^ (packetAlignment - 1)) - packetAlignment
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ioctlRegisterRings uint32 = (0x22 /*FILE_DEVICE_UNKNOWN*/ << 16) | (0x800 << 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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)
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type exchgBufRead struct {
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data [packetExchangeSize]byte
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offset uint32
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avail uint32
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type packetHeader struct {
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size uint32
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}
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type exchgBufWrite struct {
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data [packetExchangeSize]byte
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offset uint32
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type packet struct {
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packetHeader
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data [packetSizeMax]byte
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}
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type ring struct {
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head uint32
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tail uint32
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alertable int32
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data [packetCapacity + packetTrailingSize]byte
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}
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type ringDescriptor struct {
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send, receive struct {
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size uint32
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ring *ring
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tailMoved windows.Handle
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}
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}
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type NativeTun struct {
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wt *wintun.Wintun
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tunFileRead *os.File
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tunFileWrite *os.File
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tunLock sync.Mutex
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close bool
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rdBuff *exchgBufRead
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wrBuff *exchgBufWrite
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events chan Event
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errors chan error
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forcedMTU int
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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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close bool
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rings ringDescriptor
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events chan Event
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errors chan error
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forcedMTU int
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}
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func packetAlign(size uint32) uint32 {
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return (size + (packetExchangeAlignment - 1)) &^ (packetExchangeAlignment - 1)
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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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@ -102,14 +117,32 @@ func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID) (Dev
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return nil, fmt.Errorf("Unable to set name of Wintun interface: %v", err)
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}
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return &NativeTun{
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tun := &NativeTun{
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wt: wt,
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rdBuff: &exchgBufRead{},
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wrBuff: &exchgBufWrite{},
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tunDev: 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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}, nil
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}
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tun.rings.send.size = uint32(unsafe.Sizeof(ring{}))
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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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return nil, fmt.Errorf("Error creating event: %v", err)
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}
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tun.rings.receive.size = uint32(unsafe.Sizeof(ring{}))
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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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return nil, fmt.Errorf("Error creating event: %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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@ -119,9 +152,12 @@ func (tun *NativeTun) openTUN() error {
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}
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var err error
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name := tun.wt.DataFileName()
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for tun.tunFileRead == nil {
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tun.tunFileRead, err = os.OpenFile(name, os.O_RDONLY, 0)
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name, err := windows.UTF16PtrFromString(tun.wt.DataFileName())
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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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@ -130,72 +166,51 @@ func (tun *NativeTun) openTUN() error {
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}
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return err
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}
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}
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for tun.tunFileWrite == nil {
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tun.tunFileWrite, err = os.OpenFile(name, os.O_WRONLY, 0)
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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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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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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.tunFileRead != nil {
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for tun.tunDev != windows.InvalidHandle {
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tun.tunLock.Lock()
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if tun.tunFileRead == nil {
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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.tunFileRead
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tun.tunFileRead = nil
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windows.CancelIoEx(windows.Handle(t.Fd()), nil)
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err = t.Close()
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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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for tun.tunFileWrite != nil {
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tun.tunLock.Lock()
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if tun.tunFileWrite == nil {
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tun.tunLock.Unlock()
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break
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}
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t := tun.tunFileWrite
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tun.tunFileWrite = nil
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windows.CancelIoEx(windows.Handle(t.Fd()), nil)
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err2 := t.Close()
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tun.tunLock.Unlock()
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if err == nil {
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err = err2
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}
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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() (read *os.File, write *os.File, err error) {
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read, write = tun.tunFileRead, tun.tunFileWrite
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if read == nil || write == nil {
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read, write = nil, nil
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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.tunFileRead != nil && tun.tunFileWrite != nil {
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read, write = tun.tunFileRead, tun.tunFileWrite
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tun.tunLock.Unlock()
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return
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}
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err = tun.closeTUN()
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if err != nil {
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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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read, write = tun.tunFileRead, tun.tunFileWrite
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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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@ -217,18 +232,30 @@ 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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err1 := tun.closeTUN()
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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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}
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_, err2 := tun.wt.DeleteInterface()
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if err1 == nil {
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err1 = err2
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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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}
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return err1
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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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}
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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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}
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return err
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}
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func (tun *NativeTun) MTU() (int, error) {
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@ -240,6 +267,8 @@ func (tun *NativeTun) ForceMTU(mtu int) {
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tun.forcedMTU = mtu
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}
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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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select {
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case err := <-tun.errors:
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@ -248,142 +277,111 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
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}
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retries := maybeRetry(1000)
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for {
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if tun.rdBuff.offset+packetExchangeAlignment <= tun.rdBuff.avail {
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// Get packet from the exchange buffer.
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packet := tun.rdBuff.data[tun.rdBuff.offset:]
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size := *(*uint32)(unsafe.Pointer(&packet[0]))
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pSize := packetAlign(size) + packetExchangeAlignment
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if packetSizeMax < size || tun.rdBuff.avail < tun.rdBuff.offset+pSize {
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// Invalid packet size.
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tun.rdBuff.avail = 0
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continue
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}
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packet = packet[packetExchangeAlignment : packetExchangeAlignment+size]
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// Copy data.
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copy(buff[offset:], packet)
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tun.rdBuff.offset += pSize
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return int(size), nil
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}
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// Get TUN data pipe.
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file, _, err := tun.getTUN()
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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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n, err := file.Read(tun.rdBuff.data[:])
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if err != nil {
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tun.rdBuff.offset = 0
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tun.rdBuff.avail = 0
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pe, ok := err.(*os.PathError)
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if tun.close {
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return 0, os.ErrClosed
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}
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if retries > 0 && ok && (pe.Err == windows.ERROR_HANDLE_EOF || pe.Err == windows.ERROR_OPERATION_ABORTED) {
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retries--
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tun.closeTUN()
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time.Sleep(time.Millisecond * 2)
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continue
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}
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return 0, err
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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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if n == 0 {
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if retries == 0 {
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return 0, io.ErrShortBuffer
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}
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retries--
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buffTail := atomic.LoadUint32(&tun.rings.send.ring.tail)
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if buffHead == buffTail {
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windows.WaitForSingleObject(tun.rings.send.tailMoved, windows.INFINITE)
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continue
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}
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tun.rdBuff.offset = 0
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tun.rdBuff.avail = uint32(n)
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}
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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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// Note: flush() and putTunPacket() assume the caller comes only from a single thread; there's no locking.
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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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return 0, os.ErrClosed
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}
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func (tun *NativeTun) Flush() error {
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if tun.wrBuff.offset == 0 {
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return nil
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}
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defer func() {
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tun.wrBuff.offset = 0
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}()
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retries := maybeRetry(1000)
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for {
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// Get TUN data pipe.
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_, file, err := tun.getTUN()
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if err != nil {
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return err
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}
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for {
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_, err = file.Write(tun.wrBuff.data[:tun.wrBuff.offset])
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if err != nil {
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pe, ok := err.(*os.PathError)
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if tun.close {
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return os.ErrClosed
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}
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if retries > 0 && ok && pe.Err == windows.ERROR_OPERATION_ABORTED { // Adapter is paused or in low-power state.
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retries--
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time.Sleep(time.Millisecond * 2)
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continue
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}
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if retries > 0 && ok && pe.Err == windows.ERROR_HANDLE_EOF { // Adapter is going down.
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retries--
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tun.closeTUN()
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time.Sleep(time.Millisecond * 2)
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break
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}
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return err
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}
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return nil
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}
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}
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}
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func (tun *NativeTun) putTunPacket(buff []byte) error {
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size := uint32(len(buff))
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if size == 0 {
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return errors.New("Empty packet")
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}
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if size > packetSizeMax {
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return errors.New("Packet too big")
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}
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pSize := packetAlign(size) + packetExchangeAlignment
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if tun.wrBuff.offset+pSize >= packetExchangeSize {
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// Exchange buffer is full -> flush first.
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err := tun.Flush()
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if err != nil {
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return err
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}
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}
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// Write packet to the exchange buffer.
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packet := tun.wrBuff.data[tun.wrBuff.offset : tun.wrBuff.offset+pSize]
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*(*uint32)(unsafe.Pointer(&packet[0])) = size
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packet = packet[packetExchangeAlignment : packetExchangeAlignment+size]
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copy(packet, buff)
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tun.wrBuff.offset += pSize
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return nil
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}
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func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
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err := tun.putTunPacket(buff[offset:])
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if err != nil {
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return 0, err
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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 {
|
||||
return 0, errors.New("receive ring full")
|
||||
}
|
||||
|
||||
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)
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in a new issue