3341e2d444
Things work fine on Windows 8.
294 lines
7.6 KiB
Go
294 lines
7.6 KiB
Go
/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2018-2019 WireGuard LLC. All Rights Reserved.
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*/
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package tun
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import (
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"errors"
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"fmt"
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"os"
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"sync/atomic"
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"time"
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"unsafe"
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"golang.org/x/sys/windows"
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"golang.zx2c4.com/wireguard/tun/wintun"
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)
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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 = 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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size uint32
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}
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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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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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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 + (packetAlignment - 1)) &^ (packetAlignment - 1)
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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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//
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func CreateTUN(ifname string) (Device, error) {
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return CreateTUNWithRequestedGUID(ifname, nil)
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}
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//
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// CreateTUNWithRequestedGUID creates a Wintun adapter with the given name and
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// a requested GUID. Should a Wintun adapter with the same name exist, it is reused.
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//
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func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID) (Device, error) {
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var err error
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var wt *wintun.Wintun
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// Does an interface with this name already exist?
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wt, err = wintun.GetInterface(ifname)
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if err == nil {
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// If so, we delete it, in case it has weird residual configuration.
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_, err = wt.DeleteInterface()
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if err != nil {
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return nil, fmt.Errorf("Unable to delete already existing Wintun interface: %v", err)
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}
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} else if err == windows.ERROR_ALREADY_EXISTS {
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return nil, fmt.Errorf("Foreign network interface with the same name exists")
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}
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wt, _, err = wintun.CreateInterface("WireGuard Tunnel Adapter", requestedGUID)
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if err != nil {
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return nil, fmt.Errorf("Unable to create Wintun interface: %v", err)
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}
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err = wt.SetInterfaceName(ifname)
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if err != nil {
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wt.DeleteInterface()
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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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tun := &NativeTun{
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wt: wt,
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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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}
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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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tun.Close()
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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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tun.Close()
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return nil, fmt.Errorf("Error creating event: %v", err)
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}
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tun.handle, err = tun.wt.AdapterHandle()
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if err != nil {
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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) Name() (string, error) {
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return tun.wt.InterfaceName()
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}
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func (tun *NativeTun) File() *os.File {
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return nil
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}
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func (tun *NativeTun) Events() chan Event {
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return tun.events
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}
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func (tun *NativeTun) Close() error {
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tun.close = true
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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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if tun.handle != windows.InvalidHandle {
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windows.CloseHandle(tun.handle)
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}
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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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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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func (tun *NativeTun) MTU() (int, error) {
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return tun.forcedMTU, nil
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}
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// TODO: This is a temporary hack. We really need to be monitoring the interface in real time and adapting to MTU changes.
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func (tun *NativeTun) ForceMTU(mtu int) {
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tun.forcedMTU = mtu
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}
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//go:linkname procyield runtime.procyield
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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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if tun.close {
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return 0, os.ErrClosed
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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, 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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return nil
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}
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func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
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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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func (tun *NativeTun) LUID() uint64 {
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return tun.wt.LUID()
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}
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// wrap returns value modulo ring capacity
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func (rb *ring) wrap(value uint32) uint32 {
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return value & (packetCapacity - 1)
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}
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