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lightningnetwork / lnd / 15561477203

10 Jun 2025 01:54PM UTC coverage: 58.351% (-10.1%) from 68.487%
15561477203

Pull #9356

github

web-flow
Merge 6440b25db into c6d6d4c0b
Pull Request #9356: lnrpc: add incoming/outgoing channel ids filter to forwarding history request

33 of 36 new or added lines in 2 files covered. (91.67%)

28366 existing lines in 455 files now uncovered.

97715 of 167461 relevant lines covered (58.35%)

1.81 hits per line

Source File
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90.72
/chanbackup/pubsub.go
1
package chanbackup
2

3
import (
4
        "bytes"
5
        "fmt"
6
        "net"
7
        "os"
8
        "sync"
9

10
        "github.com/btcsuite/btcd/wire"
11
        "github.com/lightningnetwork/lnd/channeldb"
12
        "github.com/lightningnetwork/lnd/keychain"
13
        "github.com/lightningnetwork/lnd/lnutils"
14
)
15

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// Swapper is an interface that allows the chanbackup.SubSwapper to update the
17
// main multi backup location once it learns of new channels or that prior
18
// channels have been closed.
19
type Swapper interface {
20
        // UpdateAndSwap attempts to atomically update the main multi back up
21
        // file location with the new fully packed multi-channel backup.
22
        UpdateAndSwap(newBackup PackedMulti) error
23

24
        // ExtractMulti attempts to obtain and decode the current SCB instance
25
        // stored by the Swapper instance.
26
        ExtractMulti(keychain keychain.KeyRing) (*Multi, error)
27
}
28

29
// ChannelWithAddrs bundles an open channel along with all the addresses for
30
// the channel peer.
31
type ChannelWithAddrs struct {
32
        *channeldb.OpenChannel
33

34
        // Addrs is the set of addresses that we can use to reach the target
35
        // peer.
36
        Addrs []net.Addr
37
}
38

39
// ChannelEvent packages a new update of new channels since subscription, and
40
// channels that have been opened since prior channel event.
41
type ChannelEvent struct {
42
        // ClosedChans are the set of channels that have been closed since the
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        // last event.
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        ClosedChans []wire.OutPoint
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        // NewChans is the set of channels that have been opened since the last
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        // event.
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        NewChans []ChannelWithAddrs
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}
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// manualUpdate holds a group of channel state updates and an error channel
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// to send back an error happened upon update processing or file updating.
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type manualUpdate struct {
54
        // singles hold channels backups. They can be either new or known
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        // channels in the Swapper.
56
        singles []Single
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58
        // errChan is the channel to send an error back. If the update handling
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        // and the subsequent file updating succeeds, nil is sent.
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        // The channel must have capacity of 1 to prevent Swapper blocking.
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        errChan chan error
62
}
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// ChannelSubscription represents an intent to be notified of any updates to
65
// the primary channel state.
66
type ChannelSubscription struct {
67
        // ChanUpdates is a channel that will be sent upon once the primary
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        // channel state is updated.
69
        ChanUpdates chan ChannelEvent
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71
        // Cancel is a closure that allows the caller to cancel their
72
        // subscription and free up any resources allocated.
73
        Cancel func()
74
}
75

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// ChannelNotifier represents a system that allows the chanbackup.SubSwapper to
77
// be notified of any changes to the primary channel state.
78
type ChannelNotifier interface {
79
        // SubscribeChans requests a new channel subscription relative to the
80
        // initial set of known channels. We use the knownChans as a
81
        // synchronization point to ensure that the chanbackup.SubSwapper does
82
        // not miss any channel open or close events in the period between when
83
        // it's created, and when it requests the channel subscription.
84
        SubscribeChans(map[wire.OutPoint]struct{}) (*ChannelSubscription, error)
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}
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// SubSwapper subscribes to new updates to the open channel state, and then
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// swaps out the on-disk channel backup state in response.  This sub-system
89
// that will ensure that the multi chan backup file on disk will always be
90
// updated with the latest channel back up state. We'll receive new
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// opened/closed channels from the ChannelNotifier, then use the Swapper to
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// update the file state on disk with the new set of open channels.  This can
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// be used to implement a system that always keeps the multi-chan backup file
94
// on disk in a consistent state for safety purposes.
95
type SubSwapper struct {
96
        started sync.Once
97
        stopped sync.Once
98

99
        // backupState are the set of SCBs for all open channels we know of.
100
        backupState map[wire.OutPoint]Single
101

102
        // chanEvents is an active subscription to receive new channel state
103
        // over.
104
        chanEvents *ChannelSubscription
105

106
        manualUpdates chan manualUpdate
107

108
        // keyRing is the main key ring that will allow us to pack the new
109
        // multi backup.
110
        keyRing keychain.KeyRing
111

112
        Swapper
113

114
        quit chan struct{}
115
        wg   sync.WaitGroup
116
}
117

118
// NewSubSwapper creates a new instance of the SubSwapper given the starting
119
// set of channels, and the required interfaces to be notified of new channel
120
// updates, pack a multi backup, and swap the current best backup from its
121
// storage location.
122
func NewSubSwapper(startingChans []Single, chanNotifier ChannelNotifier,
123
        keyRing keychain.KeyRing, backupSwapper Swapper) (*SubSwapper, error) {
3✔
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3✔
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        // First, we'll subscribe to the latest set of channel updates given
3✔
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        // the set of channels we already know of.
3✔
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        knownChans := make(map[wire.OutPoint]struct{})
3✔
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        for _, chanBackup := range startingChans {
6✔
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                knownChans[chanBackup.FundingOutpoint] = struct{}{}
3✔
130
        }
3✔
131
        chanEvents, err := chanNotifier.SubscribeChans(knownChans)
3✔
132
        if err != nil {
3✔
UNCOV
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                return nil, err
×
UNCOV
134
        }
×
135

136
        // Next, we'll construct our own backup state so we can add/remove
137
        // channels that have been opened and closed.
138
        backupState := make(map[wire.OutPoint]Single)
3✔
139
        for _, chanBackup := range startingChans {
6✔
140
                backupState[chanBackup.FundingOutpoint] = chanBackup
3✔
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        }
3✔
142

143
        return &SubSwapper{
3✔
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                backupState:   backupState,
3✔
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                chanEvents:    chanEvents,
3✔
146
                keyRing:       keyRing,
3✔
147
                Swapper:       backupSwapper,
3✔
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                quit:          make(chan struct{}),
3✔
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                manualUpdates: make(chan manualUpdate),
3✔
150
        }, nil
3✔
151
}
152

153
// Start starts the chanbackup.SubSwapper.
154
func (s *SubSwapper) Start() error {
3✔
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        var startErr error
3✔
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        s.started.Do(func() {
6✔
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                log.Infof("chanbackup.SubSwapper starting")
3✔
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3✔
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                // Before we enter our main loop, we'll update the on-disk
3✔
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                // state with the latest Single state, as nodes may have new
3✔
161
                // advertised addresses.
3✔
162
                if err := s.updateBackupFile(); err != nil {
3✔
163
                        startErr = fmt.Errorf("unable to refresh backup "+
×
164
                                "file: %v", err)
×
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                        return
×
166
                }
×
167

168
                s.wg.Add(1)
3✔
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                go s.backupUpdater()
3✔
170
        })
171

172
        return startErr
3✔
173
}
174

175
// Stop signals the SubSwapper to being a graceful shutdown.
176
func (s *SubSwapper) Stop() error {
3✔
177
        s.stopped.Do(func() {
6✔
178
                log.Infof("chanbackup.SubSwapper shutting down...")
3✔
179
                defer log.Debug("chanbackup.SubSwapper shutdown complete")
3✔
180

3✔
181
                close(s.quit)
3✔
182
                s.wg.Wait()
3✔
183
        })
3✔
184
        return nil
3✔
185
}
186

187
// ManualUpdate inserts/updates channel states into the swapper. The updates
188
// are processed in another goroutine. The method waits for the updates to be
189
// fully processed and the file to be updated on-disk before returning.
190
func (s *SubSwapper) ManualUpdate(singles []Single) error {
3✔
191
        // Create the channel to send an error back. If the update handling
3✔
192
        // and the subsequent file updating succeeds, nil is sent.
3✔
193
        // The channel must have capacity of 1 to prevent Swapper blocking.
3✔
194
        errChan := make(chan error, 1)
3✔
195

3✔
196
        // Create the update object to insert into the processing loop.
3✔
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        update := manualUpdate{
3✔
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                singles: singles,
3✔
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                errChan: errChan,
3✔
200
        }
3✔
201

3✔
202
        select {
3✔
203
        case s.manualUpdates <- update:
3✔
204
        case <-s.quit:
×
205
                return fmt.Errorf("swapper stopped when sending manual update")
×
206
        }
207

208
        // Wait for processing, block on errChan.
209
        select {
3✔
210
        case err := <-errChan:
3✔
211
                if err != nil {
6✔
212
                        return fmt.Errorf("processing of manual update "+
3✔
213
                                "failed: %w", err)
3✔
214
                }
3✔
215

216
        case <-s.quit:
×
217
                return fmt.Errorf("swapper stopped when waiting for outcome")
×
218
        }
219

220
        // Success.
221
        return nil
3✔
222
}
223

224
// updateBackupFile updates the backup file in place given the current state of
225
// the SubSwapper. We accept the set of channels that were closed between this
226
// update and the last to make sure we leave them out of our backup set union.
227
func (s *SubSwapper) updateBackupFile(closedChans ...wire.OutPoint) error {
3✔
228
        // Before we pack the new set of SCBs, we'll first decode what we
3✔
229
        // already have on-disk, to make sure we can decode it (proper seed)
3✔
230
        // and that we're able to combine it with our new data.
3✔
231
        diskMulti, err := s.Swapper.ExtractMulti(s.keyRing)
3✔
232

3✔
233
        // If the file doesn't exist on disk, then that's OK as it was never
3✔
234
        // created. In this case we'll continue onwards as it isn't a critical
3✔
235
        // error.
3✔
236
        if err != nil && !os.IsNotExist(err) {
3✔
237
                return fmt.Errorf("unable to extract on disk encrypted "+
×
238
                        "SCB: %v", err)
×
239
        }
×
240

241
        // Now that we have channels stored on-disk, we'll create a new set of
242
        // the combined old and new channels to make sure we retain what's
243
        // already on-disk.
244
        //
245
        // NOTE: The ordering of this operations means that our in-memory
246
        // structure will replace what we read from disk.
247
        combinedBackup := make(map[wire.OutPoint]Single)
3✔
248
        if diskMulti != nil {
6✔
249
                for _, diskChannel := range diskMulti.StaticBackups {
6✔
250
                        chanPoint := diskChannel.FundingOutpoint
3✔
251
                        combinedBackup[chanPoint] = diskChannel
3✔
252
                }
3✔
253
        }
254
        for _, memChannel := range s.backupState {
6✔
255
                chanPoint := memChannel.FundingOutpoint
3✔
256
                if _, ok := combinedBackup[chanPoint]; ok {
6✔
257
                        log.Warnf("Replacing disk backup for ChannelPoint(%v) "+
3✔
258
                                "w/ newer version", chanPoint)
3✔
259
                }
3✔
260

261
                combinedBackup[chanPoint] = memChannel
3✔
262
        }
263

264
        // Remove the set of closed channels from the final set of backups.
265
        for _, closedChan := range closedChans {
6✔
266
                delete(combinedBackup, closedChan)
3✔
267
        }
3✔
268

269
        // With our updated channel state obtained, we'll create a new multi
270
        // from our series of singles.
271
        var newMulti Multi
3✔
272
        for _, backup := range combinedBackup {
6✔
273
                newMulti.StaticBackups = append(
3✔
274
                        newMulti.StaticBackups, backup,
3✔
275
                )
3✔
276
        }
3✔
277

278
        // Now that our multi has been assembled, we'll attempt to pack
279
        // (encrypt+encode) the new channel state to our target reader.
280
        var b bytes.Buffer
3✔
281
        err = newMulti.PackToWriter(&b, s.keyRing)
3✔
282
        if err != nil {
3✔
283
                return fmt.Errorf("unable to pack multi backup: %w", err)
×
284
        }
×
285

286
        // Finally, we'll swap out the old backup for this new one in a single
287
        // atomic step, combining the file already on-disk with this set of new
288
        // channels.
289
        err = s.Swapper.UpdateAndSwap(PackedMulti(b.Bytes()))
3✔
290
        if err != nil {
6✔
291
                return fmt.Errorf("unable to update multi backup: %w", err)
3✔
292
        }
3✔
293

294
        return nil
3✔
295
}
296

297
// backupFileUpdater is the primary goroutine of the SubSwapper which is
298
// responsible for listening for changes to the channel, and updating the
299
// persistent multi backup state with a new packed multi of the latest channel
300
// state.
301
func (s *SubSwapper) backupUpdater() {
3✔
302
        // Ensure that once we exit, we'll cancel our active channel
3✔
303
        // subscription.
3✔
304
        defer s.chanEvents.Cancel()
3✔
305
        defer s.wg.Done()
3✔
306

3✔
307
        log.Debugf("SubSwapper's backupUpdater is active!")
3✔
308

3✔
309
        for {
6✔
310
                select {
3✔
311
                // The channel state has been modified! We'll evaluate all
312
                // changes, and swap out the old packed multi with a new one
313
                // with the latest channel state.
314
                case chanUpdate := <-s.chanEvents.ChanUpdates:
3✔
315
                        oldStateSize := len(s.backupState)
3✔
316

3✔
317
                        // For all new open channels, we'll create a new SCB
3✔
318
                        // given the required information.
3✔
319
                        for _, newChan := range chanUpdate.NewChans {
6✔
320
                                log.Debugf("Adding channel %v to backup state",
3✔
321
                                        newChan.FundingOutpoint)
3✔
322

3✔
323
                                single := NewSingle(
3✔
324
                                        newChan.OpenChannel, newChan.Addrs,
3✔
325
                                )
3✔
326
                                s.backupState[newChan.FundingOutpoint] = single
3✔
327
                        }
3✔
328

329
                        // For all closed channels, we'll remove the prior
330
                        // backup state.
331
                        closedChans := make(
3✔
332
                                []wire.OutPoint, 0, len(chanUpdate.ClosedChans),
3✔
333
                        )
3✔
334
                        for i, closedChan := range chanUpdate.ClosedChans {
6✔
335
                                log.Debugf("Removing channel %v from backup "+
3✔
336
                                        "state", lnutils.NewLogClosure(
3✔
337
                                        chanUpdate.ClosedChans[i].String))
3✔
338

3✔
339
                                delete(s.backupState, closedChan)
3✔
340

3✔
341
                                closedChans = append(closedChans, closedChan)
3✔
342
                        }
3✔
343

344
                        newStateSize := len(s.backupState)
3✔
345

3✔
346
                        log.Infof("Updating on-disk multi SCB backup: "+
3✔
347
                                "num_old_chans=%v, num_new_chans=%v",
3✔
348
                                oldStateSize, newStateSize)
3✔
349

3✔
350
                        // Without new state constructed, we'll, atomically
3✔
351
                        // update the on-disk backup state.
3✔
352
                        if err := s.updateBackupFile(closedChans...); err != nil {
3✔
353
                                log.Errorf("unable to update backup file: %v",
×
354
                                        err)
×
355
                        }
×
356

357
                // We received a manual update. Handle it and update the file.
358
                case manualUpdate := <-s.manualUpdates:
3✔
359
                        oldStateSize := len(s.backupState)
3✔
360

3✔
361
                        // For all open channels, we'll create a new SCB given
3✔
362
                        // the required information.
3✔
363
                        for _, single := range manualUpdate.singles {
6✔
364
                                log.Debugf("Manual update of channel %v",
3✔
365
                                        single.FundingOutpoint)
3✔
366

3✔
367
                                s.backupState[single.FundingOutpoint] = single
3✔
368
                        }
3✔
369

370
                        newStateSize := len(s.backupState)
3✔
371

3✔
372
                        log.Infof("Updating on-disk multi SCB backup: "+
3✔
373
                                "num_old_chans=%v, num_new_chans=%v",
3✔
374
                                oldStateSize, newStateSize)
3✔
375

3✔
376
                        // Without new state constructed, we'll, atomically
3✔
377
                        // update the on-disk backup state.
3✔
378
                        err := s.updateBackupFile()
3✔
379
                        if err != nil {
6✔
380
                                log.Errorf("unable to update backup file: %v",
3✔
381
                                        err)
3✔
382
                        }
3✔
383

384
                        // Send the error (or nil) to the caller of
385
                        // ManualUpdate. The error channel must have capacity of
386
                        // 1 not to block here.
387
                        manualUpdate.errChan <- err
3✔
388

389
                // TODO(roasbeef): refresh periodically on a time basis due to
390
                // possible addr changes from node
391

392
                // Exit at once if a quit signal is detected.
393
                case <-s.quit:
3✔
394
                        return
3✔
395
                }
396
        }
397
}
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