1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
|
/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2018-2019 WireGuard LLC. All Rights Reserved.
*/
package tun
import (
"errors"
"fmt"
"os"
"sync"
"time"
"unsafe"
"golang.org/x/sys/windows"
"golang.zx2c4.com/wireguard/tun/wintun"
)
const (
packetExchangeMax uint32 = 256 // Number of packets that may be written at a time
packetExchangeAlignment uint32 = 16 // Number of bytes packets are aligned to in exchange buffers
packetSizeMax uint32 = 0xf000 - packetExchangeAlignment // Maximum packet size
packetExchangeSize uint32 = 0x100000 // Exchange buffer size (defaults to 1MiB)
retryRate = 4 // Number of retries per second to reopen device pipe
retryTimeout = 30 // Number of seconds to tolerate adapter unavailable
)
type exchgBufRead struct {
data [packetExchangeSize]byte
offset uint32
avail uint32
}
type exchgBufWrite struct {
data [packetExchangeSize]byte
offset uint32
packetNum uint32
}
type NativeTun struct {
wt *wintun.Wintun
tunFileRead *os.File
tunFileWrite *os.File
tunLock sync.Mutex
close bool
rdBuff *exchgBufRead
wrBuff *exchgBufWrite
events chan TUNEvent
errors chan error
forcedMTU int
}
func packetAlign(size uint32) uint32 {
return (size + (packetExchangeAlignment - 1)) &^ (packetExchangeAlignment - 1)
}
//
// CreateTUN creates a Wintun adapter with the given name. Should a Wintun
// adapter with the same name exist, it is reused.
//
func CreateTUN(ifname string) (TUNDevice, error) {
var err error
var wt *wintun.Wintun
// Does an interface with this name already exist?
wt, err = wintun.GetInterface(ifname, 0)
if wt == nil {
// Interface does not exist or an error occurred. Create one.
wt, _, err = wintun.CreateInterface("WireGuard Tunnel Adapter", 0)
if err != nil {
return nil, fmt.Errorf("wintun.CreateInterface: %v", err)
}
} else if err != nil {
// Foreign interface with the same name found.
// We could create a Wintun interface under a temporary name. But, should our
// process die without deleting this interface first, the interface would remain
// orphaned.
return nil, fmt.Errorf("wintun.GetInterface: %v", err)
}
err = wt.SetInterfaceName(ifname)
if err != nil {
wt.DeleteInterface(0)
return nil, fmt.Errorf("wintun.SetInterfaceName: %v", err)
}
err = wt.FlushInterface()
if err != nil {
wt.DeleteInterface(0)
return nil, fmt.Errorf("wintun.FlushInterface: %v", err)
}
return &NativeTun{
wt: wt,
rdBuff: &exchgBufRead{},
wrBuff: &exchgBufWrite{},
events: make(chan TUNEvent, 10),
errors: make(chan error, 1),
forcedMTU: 1500,
}, nil
}
func (tun *NativeTun) openTUN() error {
retries := retryTimeout * retryRate
if tun.close {
return os.ErrClosed
}
var err error
name := tun.wt.DataFileName()
for tun.tunFileRead == nil {
tun.tunFileRead, err = os.OpenFile(name, os.O_RDONLY, 0)
if err != nil {
if retries > 0 && !tun.close {
time.Sleep(time.Second / retryRate)
retries--
continue
}
return err
}
}
for tun.tunFileWrite == nil {
tun.tunFileWrite, err = os.OpenFile(name, os.O_WRONLY, 0)
if err != nil {
if retries > 0 && !tun.close {
time.Sleep(time.Second / retryRate)
retries--
continue
}
return 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 {
tun.tunLock.Lock()
if tun.tunFileWrite == nil {
tun.tunLock.Unlock()
break
}
t := tun.tunFileWrite
tun.tunFileWrite = nil
windows.CancelIoEx(windows.Handle(t.Fd()), nil)
err2 := t.Close()
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
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 {
tun.tunLock.Unlock()
return
}
err = tun.openTUN()
if err == nil {
read, write = tun.tunFileRead, tun.tunFileWrite
}
tun.tunLock.Unlock()
return
}
return
}
func (tun *NativeTun) Name() (string, error) {
return tun.wt.GetInterfaceName()
}
func (tun *NativeTun) File() *os.File {
return nil
}
func (tun *NativeTun) Events() chan TUNEvent {
return tun.events
}
func (tun *NativeTun) Close() error {
tun.close = true
err1 := tun.closeTUN()
if tun.events != nil {
close(tun.events)
}
_, _, err2 := tun.wt.DeleteInterface(0)
if err1 == nil {
err1 = err2
}
return err1
}
func (tun *NativeTun) MTU() (int, error) {
return tun.forcedMTU, nil
}
//TODO: This is a temporary hack. We really need to be monitoring the interface in real time and adapting to MTU changes.
func (tun *NativeTun) ForceMTU(mtu int) {
tun.forcedMTU = mtu
}
func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
select {
case err := <-tun.errors:
return 0, err
default:
}
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(packetExchangeAlignment + size)
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()
if err != nil {
return 0, err
}
// Fill queue.
retries := 1000
for {
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_OPERATION_ABORTED {
retries--
continue
}
if ok && pe.Err == windows.ERROR_HANDLE_EOF {
tun.closeTUN()
break
}
return 0, err
}
tun.rdBuff.offset = 0
tun.rdBuff.avail = uint32(n)
break
}
}
}
// Note: flush() and putTunPacket() assume the caller comes only from a single thread; there's no locking.
func (tun *NativeTun) Flush() error {
if tun.wrBuff.offset == 0 {
return nil
}
for {
// Get TUN data pipe.
_, file, err := tun.getTUN()
if err != nil {
return err
}
// Flush write buffer.
retries := 1000
for {
_, err = file.Write(tun.wrBuff.data[:tun.wrBuff.offset])
tun.wrBuff.packetNum = 0
tun.wrBuff.offset = 0
if err != nil {
pe, ok := err.(*os.PathError)
if tun.close {
return os.ErrClosed
}
if retries > 0 && ok && pe.Err == windows.ERROR_OPERATION_ABORTED {
retries--
continue
}
if ok && pe.Err == windows.ERROR_HANDLE_EOF {
tun.closeTUN()
break
}
return err
}
return nil
}
}
}
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(packetExchangeAlignment + size)
if tun.wrBuff.packetNum >= packetExchangeMax || tun.wrBuff.offset+pSize >= packetExchangeSize {
// Exchange buffer is full -> flush first.
err := tun.Flush()
if err != nil {
return err
}
}
// 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.packetNum++
tun.wrBuff.offset += pSize
return nil
}
func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
err := tun.putTunPacket(buff[offset:])
if err != nil {
return 0, err
}
return len(buff) - offset, nil
}
///
// LUID returns Windows adapter instance ID.
//
func (tun *NativeTun) LUID() uint64 {
return tun.wt.LUID()
}
|