forked from hashicorp/yamux
-
Notifications
You must be signed in to change notification settings - Fork 0
/
stream.go
472 lines (414 loc) · 10.2 KB
/
stream.go
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
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
package yamux
import (
"bytes"
"io"
"sync"
"sync/atomic"
"time"
)
type streamState int
const (
streamInit streamState = iota
streamSYNSent
streamSYNReceived
streamEstablished
streamLocalClose
streamRemoteClose
streamClosed
streamReset
)
// Stream is used to represent a logical stream
// within a session.
type Stream struct {
recvWindow uint32
sendWindow uint32
id uint32
session *Session
state streamState
stateLock sync.Mutex
recvBuf *bytes.Buffer
recvLock sync.Mutex
controlHdr header
controlErr chan error
controlHdrLock sync.Mutex
sendHdr header
sendErr chan error
sendLock sync.Mutex
recvNotifyCh chan struct{}
sendNotifyCh chan struct{}
readDeadline atomic.Value // time.Time
writeDeadline atomic.Value // time.Time
}
// newStream is used to construct a new stream within
// a given session for an ID
func newStream(session *Session, id uint32, state streamState) *Stream {
s := &Stream{
id: id,
session: session,
state: state,
controlHdr: header(make([]byte, headerSize)),
controlErr: make(chan error, 1),
sendHdr: header(make([]byte, headerSize)),
sendErr: make(chan error, 1),
recvWindow: initialStreamWindow,
sendWindow: initialStreamWindow,
recvNotifyCh: make(chan struct{}, 1),
sendNotifyCh: make(chan struct{}, 1),
}
s.readDeadline.Store(time.Time{})
s.writeDeadline.Store(time.Time{})
return s
}
// Session returns the associated stream session
func (s *Stream) Session() *Session {
return s.session
}
// StreamID returns the ID of this stream
func (s *Stream) StreamID() uint32 {
return s.id
}
// Read is used to read from the stream
func (s *Stream) Read(b []byte) (n int, err error) {
defer asyncNotify(s.recvNotifyCh)
START:
s.stateLock.Lock()
switch s.state {
case streamLocalClose:
fallthrough
case streamRemoteClose:
fallthrough
case streamClosed:
s.recvLock.Lock()
if s.recvBuf == nil || s.recvBuf.Len() == 0 {
s.recvLock.Unlock()
s.stateLock.Unlock()
return 0, io.EOF
}
s.recvLock.Unlock()
case streamReset:
s.stateLock.Unlock()
return 0, ErrConnectionReset
}
s.stateLock.Unlock()
// If there is no data available, block
s.recvLock.Lock()
if s.recvBuf == nil || s.recvBuf.Len() == 0 {
s.recvLock.Unlock()
goto WAIT
}
// Read any bytes
n, _ = s.recvBuf.Read(b)
s.recvLock.Unlock()
// Send a window update potentially
err = s.sendWindowUpdate()
return n, err
WAIT:
var timeout <-chan time.Time
var timer *time.Timer
readDeadline := s.readDeadline.Load().(time.Time)
if !readDeadline.IsZero() {
delay := readDeadline.Sub(time.Now())
timer = time.NewTimer(delay)
timeout = timer.C
}
select {
case <-s.recvNotifyCh:
if timer != nil {
timer.Stop()
}
goto START
case <-timeout:
return 0, ErrTimeout
}
}
// Write is used to write to the stream
func (s *Stream) Write(b []byte) (n int, err error) {
s.sendLock.Lock()
defer s.sendLock.Unlock()
total := 0
for total < len(b) {
n, err := s.write(b[total:])
total += n
if err != nil {
return total, err
}
}
return total, nil
}
// write is used to write to the stream, may return on
// a short write.
func (s *Stream) write(b []byte) (n int, err error) {
var flags uint16
var max uint32
var body io.Reader
START:
s.stateLock.Lock()
switch s.state {
case streamLocalClose:
fallthrough
case streamClosed:
s.stateLock.Unlock()
return 0, ErrStreamClosed
case streamReset:
s.stateLock.Unlock()
return 0, ErrConnectionReset
}
s.stateLock.Unlock()
// If there is no data available, block
window := atomic.LoadUint32(&s.sendWindow)
if window == 0 {
goto WAIT
}
// Determine the flags if any
flags = s.sendFlags()
// Send up to our send window
max = min(window, uint32(len(b)))
body = bytes.NewReader(b[:max])
// Send the header
s.sendHdr.encode(typeData, flags, s.id, max)
if err = s.session.waitForSendErr(s.sendHdr, body, s.sendErr); err != nil {
return 0, err
}
// Reduce our send window
atomic.AddUint32(&s.sendWindow, ^uint32(max-1))
// Unlock
return int(max), err
WAIT:
var timeout <-chan time.Time
writeDeadline := s.writeDeadline.Load().(time.Time)
if !writeDeadline.IsZero() {
delay := writeDeadline.Sub(time.Now())
timeout = time.After(delay)
}
select {
case <-s.sendNotifyCh:
goto START
case <-timeout:
return 0, ErrTimeout
}
return 0, nil
}
// sendFlags determines any flags that are appropriate
// based on the current stream state
func (s *Stream) sendFlags() uint16 {
s.stateLock.Lock()
defer s.stateLock.Unlock()
var flags uint16
switch s.state {
case streamInit:
flags |= flagSYN
s.state = streamSYNSent
case streamSYNReceived:
flags |= flagACK
s.state = streamEstablished
}
return flags
}
// sendWindowUpdate potentially sends a window update enabling
// further writes to take place. Must be invoked with the lock.
func (s *Stream) sendWindowUpdate() error {
s.controlHdrLock.Lock()
defer s.controlHdrLock.Unlock()
// Determine the delta update
max := s.session.config.MaxStreamWindowSize
var bufLen uint32
s.recvLock.Lock()
if s.recvBuf != nil {
bufLen = uint32(s.recvBuf.Len())
}
delta := (max - bufLen) - s.recvWindow
// Determine the flags if any
flags := s.sendFlags()
// Check if we can omit the update
if delta < (max/2) && flags == 0 {
s.recvLock.Unlock()
return nil
}
// Update our window
s.recvWindow += delta
s.recvLock.Unlock()
// Send the header
s.controlHdr.encode(typeWindowUpdate, flags, s.id, delta)
if err := s.session.waitForSendErr(s.controlHdr, nil, s.controlErr); err != nil {
return err
}
return nil
}
// sendClose is used to send a FIN
func (s *Stream) sendClose() error {
s.controlHdrLock.Lock()
defer s.controlHdrLock.Unlock()
flags := s.sendFlags()
flags |= flagFIN
s.controlHdr.encode(typeWindowUpdate, flags, s.id, 0)
if err := s.session.waitForSendErr(s.controlHdr, nil, s.controlErr); err != nil {
return err
}
return nil
}
// Close is used to close the stream
func (s *Stream) Close() error {
closeStream := false
s.stateLock.Lock()
switch s.state {
// Opened means we need to signal a close
case streamSYNSent:
fallthrough
case streamSYNReceived:
fallthrough
case streamEstablished:
s.state = streamLocalClose
goto SEND_CLOSE
case streamLocalClose:
case streamRemoteClose:
s.state = streamClosed
closeStream = true
goto SEND_CLOSE
case streamClosed:
case streamReset:
default:
panic("unhandled state")
}
s.stateLock.Unlock()
return nil
SEND_CLOSE:
s.stateLock.Unlock()
s.sendClose()
s.notifyWaiting()
if closeStream {
s.session.closeStream(s.id)
}
return nil
}
// forceClose is used for when the session is exiting
func (s *Stream) forceClose() {
s.stateLock.Lock()
s.state = streamClosed
s.stateLock.Unlock()
s.notifyWaiting()
}
// processFlags is used to update the state of the stream
// based on set flags, if any. Lock must be held
func (s *Stream) processFlags(flags uint16) error {
// Close the stream without holding the state lock
closeStream := false
defer func() {
if closeStream {
s.session.closeStream(s.id)
}
}()
s.stateLock.Lock()
defer s.stateLock.Unlock()
if flags&flagACK == flagACK {
if s.state == streamSYNSent {
s.state = streamEstablished
}
s.session.establishStream(s.id)
}
if flags&flagFIN == flagFIN {
switch s.state {
case streamSYNSent:
fallthrough
case streamSYNReceived:
fallthrough
case streamEstablished:
s.state = streamRemoteClose
s.notifyWaiting()
case streamLocalClose:
s.state = streamClosed
closeStream = true
s.notifyWaiting()
default:
s.session.logger.Printf("[ERR] yamux: unexpected FIN flag in state %d", s.state)
return ErrUnexpectedFlag
}
}
if flags&flagRST == flagRST {
s.state = streamReset
closeStream = true
s.notifyWaiting()
}
return nil
}
// notifyWaiting notifies all the waiting channels
func (s *Stream) notifyWaiting() {
asyncNotify(s.recvNotifyCh)
asyncNotify(s.sendNotifyCh)
}
// incrSendWindow updates the size of our send window
func (s *Stream) incrSendWindow(hdr header, flags uint16) error {
if err := s.processFlags(flags); err != nil {
return err
}
// Increase window, unblock a sender
atomic.AddUint32(&s.sendWindow, hdr.Length())
asyncNotify(s.sendNotifyCh)
return nil
}
// readData is used to handle a data frame
func (s *Stream) readData(hdr header, flags uint16, conn io.Reader) error {
if err := s.processFlags(flags); err != nil {
return err
}
// Check that our recv window is not exceeded
length := hdr.Length()
if length == 0 {
return nil
}
// Wrap in a limited reader
conn = &io.LimitedReader{R: conn, N: int64(length)}
// Copy into buffer
s.recvLock.Lock()
if length > s.recvWindow {
s.session.logger.Printf("[ERR] yamux: receive window exceeded (stream: %d, remain: %d, recv: %d)", s.id, s.recvWindow, length)
return ErrRecvWindowExceeded
}
if s.recvBuf == nil {
// Allocate the receive buffer just-in-time to fit the full data frame.
// This way we can read in the whole packet without further allocations.
s.recvBuf = bytes.NewBuffer(make([]byte, 0, length))
}
if _, err := io.Copy(s.recvBuf, conn); err != nil {
s.session.logger.Printf("[ERR] yamux: Failed to read stream data: %v", err)
s.recvLock.Unlock()
return err
}
// Decrement the receive window
s.recvWindow -= length
s.recvLock.Unlock()
// Unblock any readers
asyncNotify(s.recvNotifyCh)
return nil
}
// SetDeadline sets the read and write deadlines
func (s *Stream) SetDeadline(t time.Time) error {
if err := s.SetReadDeadline(t); err != nil {
return err
}
if err := s.SetWriteDeadline(t); err != nil {
return err
}
return nil
}
// SetReadDeadline sets the deadline for blocked and future Read calls.
func (s *Stream) SetReadDeadline(t time.Time) error {
s.readDeadline.Store(t)
asyncNotify(s.recvNotifyCh)
return nil
}
// SetWriteDeadline sets the deadline for blocked and future Write calls
func (s *Stream) SetWriteDeadline(t time.Time) error {
s.writeDeadline.Store(t)
asyncNotify(s.sendNotifyCh)
return nil
}
// Shrink is used to compact the amount of buffers utilized
// This is useful when using Yamux in a connection pool to reduce
// the idle memory utilization.
func (s *Stream) Shrink() {
s.recvLock.Lock()
if s.recvBuf != nil && s.recvBuf.Len() == 0 {
s.recvBuf = nil
}
s.recvLock.Unlock()
}