/
session.go
461 lines (408 loc) · 14.1 KB
/
session.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
// Copyright 2016 The Mellium Contributors.
// Use of this source code is governed by the BSD 2-clause
// license that can be found in the LICENSE file.
package xmpp
import (
"context"
"encoding/xml"
"errors"
"io"
"sync"
"mellium.im/xmlstream"
"mellium.im/xmpp/internal"
"mellium.im/xmpp/internal/ns"
"mellium.im/xmpp/jid"
"mellium.im/xmpp/stream"
)
// Errors returned by the XMPP package.
var (
ErrInputStreamClosed = errors.New("xmpp: attempted to read token from closed stream")
ErrOutputStreamClosed = errors.New("xmpp: attempted to write token to closed stream")
)
// SessionState is a bitmask that represents the current state of an XMPP
// session. For a description of each bit, see the various SessionState typed
// constants.
type SessionState uint8
const (
// Secure indicates that the underlying connection has been secured. For
// instance, after STARTTLS has been performed or if a pre-secured connection
// is being used such as websockets over HTTPS.
Secure SessionState = 1 << iota
// Authn indicates that the session has been authenticated (probably with
// SASL).
Authn
// Ready indicates that the session is fully negotiated and that XMPP stanzas
// may be sent and received.
Ready
// Received indicates that the session was initiated by a foreign entity.
Received
// OutputStreamClosed indicates that the output stream has been closed with a
// stream end tag. When set all write operations will return an error even if
// the underlying TCP connection is still open.
OutputStreamClosed
// InputStreamClosed indicates that the input stream has been closed with a
// stream end tag. When set all read operations will return an error.
InputStreamClosed
)
// A Session represents an XMPP session comprising an input and an output XML
// stream.
type Session struct {
conn *Conn
state SessionState
slock sync.RWMutex
origin *jid.JID
location *jid.JID
// The stream feature namespaces advertised for the current streams.
features map[string]interface{}
// The negotiated features (by namespace) for the current session.
negotiated map[string]struct{}
in struct {
sync.Mutex
internal.StreamInfo
d xml.TokenReader
ctx context.Context
cancel context.CancelFunc
}
out struct {
internal.StreamInfo
e xmlstream.TokenWriter
}
}
// Negotiator is a function that can be passed to NegotiateSession to perform
// custom session negotiation. This can be used for creating custom stream
// initialization logic that does not use XMPP feature negotiation such as the
// connection mechanism described in XEP-0114: Jabber Component Protocol.
// Normally NewClientSession or NewServerSession should be used instead.
//
// If a Negotiator is passed into NegotiateSession it will be called repeatedly
// until a mask is returned with the Ready bit set. Each time Negotiator is
// called any bits set in the state mask that it returns will be set on the
// session state and any cache value that is returned will be passed back in
// during the next iteration. If a new io.ReadWriter is returned, it is set as
// the session's underlying io.ReadWriter and the internal session state
// (encoders, decoders, etc.) will be reset.
type Negotiator func(ctx context.Context, session *Session, data interface{}) (mask SessionState, rw io.ReadWriter, cache interface{}, err error)
// NegotiateSession creates an XMPP session using a custom negotiate function.
// Calling NegotiateSession with a nil Negotiator panics.
//
// For more information see the Negotiator type.
func NegotiateSession(ctx context.Context, location, origin *jid.JID, rw io.ReadWriter, negotiate Negotiator) (*Session, error) {
if negotiate == nil {
panic("xmpp: attempted to negotiate session with nil negotiator")
}
s := &Session{
conn: newConn(rw),
origin: origin,
location: location,
features: make(map[string]interface{}),
negotiated: make(map[string]struct{}),
}
s.in.d = xml.NewDecoder(s.conn)
s.out.e = xml.NewEncoder(s.conn)
s.in.ctx, s.in.cancel = context.WithCancel(context.Background())
// Call negotiate until the ready bit is set.
var data interface{} = true
for s.state&Ready == 0 {
var mask SessionState
var rw io.ReadWriter
var err error
mask, rw, data, err = negotiate(ctx, s, data)
if err != nil {
return s, err
}
if rw != nil {
s.features = make(map[string]interface{})
s.negotiated = make(map[string]struct{})
s.conn = newConn(rw)
s.in.d = xml.NewDecoder(s.conn)
s.out.e = xml.NewEncoder(s.conn)
}
s.state |= mask
}
s.out.e = stanzaAddID(s.out.e)
return s, nil
}
type wrapWriter struct {
encode func(t xml.Token) error
flush func() error
}
func (w wrapWriter) EncodeToken(t xml.Token) error { return w.encode(t) }
func (w wrapWriter) Flush() error { return w.flush() }
func stanzaAddID(w xmlstream.TokenWriter) xmlstream.TokenWriter {
depth := 0
return wrapWriter{
encode: func(t xml.Token) error {
tokswitch:
switch tok := t.(type) {
case xml.StartElement:
depth++
if depth == 1 && tok.Name.Local == "iq" {
for _, attr := range tok.Attr {
if attr.Name.Local == "id" {
break tokswitch
}
}
tok.Attr = append(tok.Attr, xml.Attr{
Name: xml.Name{Local: "id"},
Value: internal.RandomID(),
})
t = tok
}
case xml.EndElement:
depth--
}
return w.EncodeToken(t)
},
flush: w.Flush,
}
}
// NewClientSession attempts to use an existing connection (or any
// io.ReadWriter) to negotiate an XMPP client-to-server session.
// If the provided context is canceled before stream negotiation is complete an
// error is returned.
// After stream negotiation if the context is canceled it has no effect.
func NewClientSession(ctx context.Context, origin *jid.JID, lang string, rw io.ReadWriter, features ...StreamFeature) (*Session, error) {
return NegotiateSession(ctx, origin.Domain(), origin, rw, negotiator(false, lang, features))
}
// NewServerSession attempts to use an existing connection (or any
// io.ReadWriter) to negotiate an XMPP server-to-server session.
// If the provided context is canceled before stream negotiation is complete an
// error is returned.
// After stream negotiation if the context is canceled it has no effect.
func NewServerSession(ctx context.Context, location, origin *jid.JID, lang string, rw io.ReadWriter, features ...StreamFeature) (*Session, error) {
return NegotiateSession(ctx, location, origin, rw, negotiator(true, lang, features))
}
// Serve decodes incoming XML tokens from the connection and delegates handling
// them to h.
// If an error is returned from the handler and it is of type stanza.Error or
// stream.Error, the error is marshaled and sent over the XML stream.
// If any other error type is returned, it is marshaled as an
// undefined-condition StreamError.
// If a stream error is received while serving it is not passed to the handler.
// Instead, Serve unmarshals the error, closes the session, and returns it (h
// handles stanza level errors, the session handles stream level errors).
//
// If Serve is called concurrently the second invocation blocks until the first
// returns.
// If the input stream is closed, Serve returns.
// Serve does not close the output stream.
func (s *Session) Serve(h Handler) error {
s.in.Lock()
defer s.in.Unlock()
return s.handleInputStream(h)
}
// sendError transmits an error on the session. If the error is not a standard
// stream error an UndefinedCondition stream error is sent.
// If an error is returned (the original error or a different one), it has not
// been handled fully and must be handled by the caller.
func (s *Session) sendError(err error) (e error) {
switch typErr := err.(type) {
case stream.Error:
if _, e = typErr.WriteXML(s); e != nil {
return e
}
if e = s.Close(); e != nil {
return e
}
return err
}
// TODO: What should we do here? RFC 6120 §4.9.3.21. undefined-condition
// says:
//
// The error condition is not one of those defined by the other
// conditions in this list; this error condition SHOULD NOT be used
// except in conjunction with an application-specific condition.
if _, e = stream.UndefinedCondition.WriteXML(s); e != nil {
return e
}
return err
}
func (s *Session) handleInputStream(handler Handler) (err error) {
defer func() {
e := s.Close()
if err == nil {
err = e
}
}()
discard := xmlstream.Discard()
for {
select {
case <-s.in.ctx.Done():
return s.in.ctx.Err()
default:
}
tok, err := s.Token()
// TODO: If this is a network issue we should return it, if not we should
// handle it.
if err != nil {
return s.sendError(err)
}
var start xml.StartElement
switch t := tok.(type) {
case xml.StartElement:
start = t
case xml.EndElement:
if t.Name.Space == ns.Stream && t.Name.Local == "stream" {
return nil
}
// If this is a stream level end element but not </stream:stream>,
// something is really weird…
return s.sendError(stream.BadFormat)
default:
// If this isn't a start element, the stream is in a bad state.
return s.sendError(stream.BadFormat)
}
rw := struct {
xml.TokenReader
xmlstream.TokenWriter
}{
TokenReader: xmlstream.Inner(s),
TokenWriter: s,
}
// Handle stream errors and unknown stream namespaced tokens first, before
// delegating to the normal handler.
if start.Name.Space == ns.Stream {
switch start.Name.Local {
case "error":
// TODO: Unmarshal the error and return it.
return nil
default:
return s.sendError(stream.UnsupportedStanzaType)
}
}
if err = handler.HandleXMPP(rw, &start); err != nil {
return s.sendError(err)
}
// Advance to the end of the current element before attempting to read the
// next.
//
// TODO: Error handling should be the same here as it would be for the rest
// of this loop.
_, err = xmlstream.Copy(discard, rw)
if err != nil {
return s.sendError(err)
}
}
}
// Feature checks if a feature with the given namespace was advertised
// by the server for the current stream. If it was data will be the canonical
// representation of the feature as returned by the feature's Parse function.
func (s *Session) Feature(namespace string) (data interface{}, ok bool) {
// TODO: Make the features struct actually store the parsed representation.
data, ok = s.features[namespace]
return data, ok
}
// Conn returns the Session's backing connection.
//
// This should almost never be read from or written to, but is useful during
// stream negotiation for wrapping the existing connection in a new layer (eg.
// compression or TLS).
func (s *Session) Conn() *Conn {
return s.conn
}
// Token satisfies the xml.TokenReader interface for Session.
func (s *Session) Token() (xml.Token, error) {
s.slock.RLock()
defer s.slock.RUnlock()
if s.state&InputStreamClosed == InputStreamClosed {
return nil, ErrInputStreamClosed
}
return s.in.d.Token()
}
// EncodeToken satisfies the xmlstream.TokenWriter interface.
func (s *Session) EncodeToken(t xml.Token) error {
s.slock.RLock()
defer s.slock.RUnlock()
if s.state&OutputStreamClosed == OutputStreamClosed {
return ErrOutputStreamClosed
}
return s.out.e.EncodeToken(t)
}
// Flush satisfies the xmlstream.TokenWriter interface.
func (s *Session) Flush() error {
s.slock.RLock()
defer s.slock.RUnlock()
if s.state&OutputStreamClosed == OutputStreamClosed {
return ErrOutputStreamClosed
}
return s.out.e.Flush()
}
// Close ends the output stream (by sending a closing </stream:stream> token).
// It does not close the underlying connection.
// Calling Close() multiple times will only result in one closing
// </stream:stream> being sent.
func (s *Session) Close() error {
s.slock.Lock()
defer s.slock.Unlock()
if s.state&OutputStreamClosed == OutputStreamClosed {
return nil
}
s.state |= OutputStreamClosed
// We wrote the opening stream instead of encoding it, so do the same with the
// closing to ensure that the encoder doesn't think the tokens are mismatched.
_, err := s.Conn().Write([]byte(`</stream:stream>`))
return err
}
// State returns the current state of the session. For more information, see the
// SessionState type.
func (s *Session) State() SessionState {
s.slock.RLock()
defer s.slock.RUnlock()
return s.state
}
// LocalAddr returns the Origin address for initiated connections, or the
// Location for received connections.
func (s *Session) LocalAddr() *jid.JID {
s.slock.RLock()
defer s.slock.RUnlock()
if (s.state & Received) == Received {
return s.location
}
if s.origin != nil {
return s.origin
}
return s.origin
}
// RemoteAddr returns the Location address for initiated connections, or the
// Origin address for received connections.
func (s *Session) RemoteAddr() *jid.JID {
s.slock.RLock()
defer s.slock.RUnlock()
if (s.state & Received) == Received {
return s.origin
}
return s.location
}
func negotiator(s2s bool, lang string, features []StreamFeature) Negotiator {
return func(ctx context.Context, s *Session, doRestart interface{}) (mask SessionState, rw io.ReadWriter, restartNext interface{}, err error) {
// Loop for as long as we're not done negotiating features or a stream restart
// is still required.
if rst, ok := doRestart.(bool); ok && rst {
if (s.state & Received) == Received {
// If we're the receiving entity wait for a new stream, then send one in
// response.
s.in.StreamInfo, err = internal.ExpectNewStream(ctx, s.in.d, s.State()&Received == Received)
if err != nil {
return mask, nil, false, err
}
s.out.StreamInfo, err = internal.SendNewStream(s.Conn(), s2s, internal.DefaultVersion, lang, s.location.String(), s.origin.String(), internal.RandomID())
if err != nil {
return mask, nil, false, err
}
} else {
// If we're the initiating entity, send a new stream and then wait for
// one in response.
s.out.StreamInfo, err = internal.SendNewStream(s.Conn(), s2s, internal.DefaultVersion, lang, s.location.String(), s.origin.String(), "")
if err != nil {
return mask, nil, false, err
}
s.in.StreamInfo, err = internal.ExpectNewStream(ctx, s.in.d, s.State()&Received == Received)
if err != nil {
return mask, nil, false, err
}
}
}
mask, rw, err = negotiateFeatures(ctx, s, features)
return mask, rw, rw != nil, err
}
}