-
Notifications
You must be signed in to change notification settings - Fork 0
/
htlc_timeout_resolver.go
747 lines (646 loc) · 24.6 KB
/
htlc_timeout_resolver.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
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
package contractcourt
import (
"encoding/binary"
"fmt"
"io"
"math"
"sync"
"github.com/brronsuite/brond/wire"
"github.com/brronsuite/lnd/chainntnfs"
"github.com/brronsuite/lnd/channeldb"
"github.com/brronsuite/lnd/input"
"github.com/brronsuite/lnd/lntypes"
"github.com/brronsuite/lnd/lnwallet"
"github.com/brronsuite/lnd/lnwire"
"github.com/brronsuite/lnd/sweep"
"github.com/btcsuite/btcutil"
"github.com/davecgh/go-spew/spew"
)
// htlcTimeoutResolver is a ContractResolver that's capable of resolving an
// outgoing HTLC. The HTLC may be on our commitment transaction, or on the
// commitment transaction of the remote party. An output on our commitment
// transaction is considered fully resolved once the second-level transaction
// has been confirmed (and reached a sufficient depth). An output on the
// commitment transaction of the remote party is resolved once we detect a
// spend of the direct HTLC output using the timeout clause.
type htlcTimeoutResolver struct {
// htlcResolution contains all the information required to properly
// resolve this outgoing HTLC.
htlcResolution lnwallet.OutgoingHtlcResolution
// outputIncubating returns true if we've sent the output to the output
// incubator (utxo nursery).
outputIncubating bool
// resolved reflects if the contract has been fully resolved or not.
resolved bool
// broadcastHeight is the height that the original contract was
// broadcast to the main-chain at. We'll use this value to bound any
// historical queries to the chain for spends/confirmations.
//
// TODO(roasbeef): wrap above into definite resolution embedding?
broadcastHeight uint32
// htlc contains information on the htlc that we are resolving on-chain.
htlc channeldb.HTLC
// channelInitiator denotes whether the party responsible for resolving
// the contract initiated the channel.
channelInitiator bool
// leaseExpiry denotes the additional waiting period the contract must
// hold until it can be resolved. This waiting period is known as the
// expiration of a script-enforced leased channel and only applies to
// the channel initiator.
//
// NOTE: This value should only be set when the contract belongs to a
// leased channel.
leaseExpiry uint32
// currentReport stores the current state of the resolver for reporting
// over the rpc interface. This should only be reported in case we have
// a non-nil SignDetails on the htlcResolution, otherwise the nursery
// will produce reports.
currentReport ContractReport
// reportLock prevents concurrent access to the resolver report.
reportLock sync.Mutex
contractResolverKit
}
// newTimeoutResolver instantiates a new timeout htlc resolver.
func newTimeoutResolver(res lnwallet.OutgoingHtlcResolution,
broadcastHeight uint32, htlc channeldb.HTLC,
resCfg ResolverConfig) *htlcTimeoutResolver {
h := &htlcTimeoutResolver{
contractResolverKit: *newContractResolverKit(resCfg),
htlcResolution: res,
broadcastHeight: broadcastHeight,
htlc: htlc,
}
h.initReport()
return h
}
// ResolverKey returns an identifier which should be globally unique for this
// particular resolver within the chain the original contract resides within.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcTimeoutResolver) ResolverKey() []byte {
// The primary key for this resolver will be the outpoint of the HTLC
// on the commitment transaction itself. If this is our commitment,
// then the output can be found within the signed timeout tx,
// otherwise, it's just the ClaimOutpoint.
var op wire.OutPoint
if h.htlcResolution.SignedTimeoutTx != nil {
op = h.htlcResolution.SignedTimeoutTx.TxIn[0].PreviousOutPoint
} else {
op = h.htlcResolution.ClaimOutpoint
}
key := newResolverID(op)
return key[:]
}
const (
// expectedRemoteWitnessSuccessSize is the expected size of the witness
// on the remote commitment transaction for an outgoing HTLC that is
// swept on-chain by them with pre-image.
expectedRemoteWitnessSuccessSize = 5
// remotePreimageIndex index within the witness on the remote
// commitment transaction that will hold they pre-image if they go to
// sweep it on chain.
remotePreimageIndex = 3
// localPreimageIndex is the index within the witness on the local
// commitment transaction for an outgoing HTLC that will hold the
// pre-image if the remote party sweeps it.
localPreimageIndex = 1
)
// claimCleanUp is a helper method that's called once the HTLC output is spent
// by the remote party. It'll extract the preimage, add it to the global cache,
// and finally send the appropriate clean up message.
func (h *htlcTimeoutResolver) claimCleanUp(
commitSpend *chainntnfs.SpendDetail) (ContractResolver, error) {
// Depending on if this is our commitment or not, then we'll be looking
// for a different witness pattern.
spenderIndex := commitSpend.SpenderInputIndex
spendingInput := commitSpend.SpendingTx.TxIn[spenderIndex]
log.Infof("%T(%v): extracting preimage! remote party spent "+
"HTLC with tx=%v", h, h.htlcResolution.ClaimOutpoint,
spew.Sdump(commitSpend.SpendingTx))
// If this is the remote party's commitment, then we'll be looking for
// them to spend using the second-level success transaction.
var preimageBytes []byte
if h.htlcResolution.SignedTimeoutTx == nil {
// The witness stack when the remote party sweeps the output to
// them looks like:
//
// * <0> <sender sig> <recvr sig> <preimage> <witness script>
preimageBytes = spendingInput.Witness[remotePreimageIndex]
} else {
// Otherwise, they'll be spending directly from our commitment
// output. In which case the witness stack looks like:
//
// * <sig> <preimage> <witness script>
preimageBytes = spendingInput.Witness[localPreimageIndex]
}
preimage, err := lntypes.MakePreimage(preimageBytes)
if err != nil {
return nil, fmt.Errorf("unable to create pre-image from "+
"witness: %v", err)
}
log.Infof("%T(%v): extracting preimage=%v from on-chain "+
"spend!", h, h.htlcResolution.ClaimOutpoint, preimage)
// With the preimage obtained, we can now add it to the global cache.
if err := h.PreimageDB.AddPreimages(preimage); err != nil {
log.Errorf("%T(%v): unable to add witness to cache",
h, h.htlcResolution.ClaimOutpoint)
}
var pre [32]byte
copy(pre[:], preimage[:])
// Finally, we'll send the clean up message, mark ourselves as
// resolved, then exit.
if err := h.DeliverResolutionMsg(ResolutionMsg{
SourceChan: h.ShortChanID,
HtlcIndex: h.htlc.HtlcIndex,
PreImage: &pre,
}); err != nil {
return nil, err
}
h.resolved = true
// Checkpoint our resolver with a report which reflects the preimage
// claim by the remote party.
amt := btcutil.Amount(h.htlcResolution.SweepSignDesc.Output.Value)
report := &channeldb.ResolverReport{
OutPoint: h.htlcResolution.ClaimOutpoint,
Amount: amt,
ResolverType: channeldb.ResolverTypeOutgoingHtlc,
ResolverOutcome: channeldb.ResolverOutcomeClaimed,
SpendTxID: commitSpend.SpenderTxHash,
}
return nil, h.Checkpoint(h, report)
}
// chainDetailsToWatch returns the output and script which we use to watch for
// spends from the direct HTLC output on the commitment transaction.
//
// TODO(joostjager): output already set properly in
// lnwallet.newOutgoingHtlcResolution? And script too?
func (h *htlcTimeoutResolver) chainDetailsToWatch() (*wire.OutPoint, []byte, error) {
// If there's no timeout transaction, then the claim output is the
// output directly on the commitment transaction, so we'll just use
// that.
if h.htlcResolution.SignedTimeoutTx == nil {
outPointToWatch := h.htlcResolution.ClaimOutpoint
scriptToWatch := h.htlcResolution.SweepSignDesc.Output.PkScript
return &outPointToWatch, scriptToWatch, nil
}
// If this is the remote party's commitment, then we'll need to grab
// watch the output that our timeout transaction points to. We can
// directly grab the outpoint, then also extract the witness script
// (the last element of the witness stack) to re-construct the pkScript
// we need to watch.
outPointToWatch := h.htlcResolution.SignedTimeoutTx.TxIn[0].PreviousOutPoint
witness := h.htlcResolution.SignedTimeoutTx.TxIn[0].Witness
scriptToWatch, err := input.WitnessScriptHash(witness[len(witness)-1])
if err != nil {
return nil, nil, err
}
return &outPointToWatch, scriptToWatch, nil
}
// isSuccessSpend returns true if the passed spend on the specified commitment
// is a success spend that reveals the pre-image or not.
func isSuccessSpend(spend *chainntnfs.SpendDetail, localCommit bool) bool {
// Based on the spending input index and transaction, obtain the
// witness that tells us what type of spend this is.
spenderIndex := spend.SpenderInputIndex
spendingInput := spend.SpendingTx.TxIn[spenderIndex]
spendingWitness := spendingInput.Witness
// If this is the remote commitment then the only possible spends for
// outgoing HTLCs are:
//
// RECVR: <0> <sender sig> <recvr sig> <preimage> (2nd level success spend)
// REVOK: <sig> <key>
// SENDR: <sig> 0
//
// In this case, if 5 witness elements are present (factoring the
// witness script), and the 3rd element is the size of the pre-image,
// then this is a remote spend. If not, then we swept it ourselves, or
// revoked their output.
if !localCommit {
return len(spendingWitness) == expectedRemoteWitnessSuccessSize &&
len(spendingWitness[remotePreimageIndex]) == lntypes.HashSize
}
// Otherwise, for our commitment, the only possible spends for an
// outgoing HTLC are:
//
// SENDR: <0> <sendr sig> <recvr sig> <0> (2nd level timeout)
// RECVR: <recvr sig> <preimage>
// REVOK: <revoke sig> <revoke key>
//
// So the only success case has the pre-image as the 2nd (index 1)
// element in the witness.
return len(spendingWitness[localPreimageIndex]) == lntypes.HashSize
}
// Resolve kicks off full resolution of an outgoing HTLC output. If it's our
// commitment, it isn't resolved until we see the second level HTLC txn
// confirmed. If it's the remote party's commitment, we don't resolve until we
// see a direct sweep via the timeout clause.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcTimeoutResolver) Resolve() (ContractResolver, error) {
// If we're already resolved, then we can exit early.
if h.resolved {
return nil, nil
}
// Start by spending the HTLC output, either by broadcasting the
// second-level timeout transaction, or directly if this is the remote
// commitment.
commitSpend, err := h.spendHtlcOutput()
if err != nil {
return nil, err
}
// If the spend reveals the pre-image, then we'll enter the clean up
// workflow to pass the pre-image back to the incoming link, add it to
// the witness cache, and exit.
if isSuccessSpend(commitSpend, h.htlcResolution.SignedTimeoutTx != nil) {
log.Infof("%T(%v): HTLC has been swept with pre-image by "+
"remote party during timeout flow! Adding pre-image to "+
"witness cache", h.htlcResolution.ClaimOutpoint)
return h.claimCleanUp(commitSpend)
}
log.Infof("%T(%v): resolving htlc with incoming fail msg, fully "+
"confirmed", h, h.htlcResolution.ClaimOutpoint)
// At this point, the second-level transaction is sufficiently
// confirmed, or a transaction directly spending the output is.
// Therefore, we can now send back our clean up message, failing the
// HTLC on the incoming link.
failureMsg := &lnwire.FailPermanentChannelFailure{}
if err := h.DeliverResolutionMsg(ResolutionMsg{
SourceChan: h.ShortChanID,
HtlcIndex: h.htlc.HtlcIndex,
Failure: failureMsg,
}); err != nil {
return nil, err
}
// Depending on whether this was a local or remote commit, we must
// handle the spending transaction accordingly.
return h.handleCommitSpend(commitSpend)
}
// spendHtlcOutput handles the initial spend of an HTLC output via the timeout
// clause. If this is our local commitment, the second-level timeout TX will be
// used to spend the output into the next stage. If this is the remote
// commitment, the output will be swept directly without the timeout
// transaction.
func (h *htlcTimeoutResolver) spendHtlcOutput() (*chainntnfs.SpendDetail, error) {
switch {
// If we have non-nil SignDetails, this means that have a 2nd level
// HTLC transaction that is signed using sighash SINGLE|ANYONECANPAY
// (the case for anchor type channels). In this case we can re-sign it
// and attach fees at will. We let the sweeper handle this job.
case h.htlcResolution.SignDetails != nil && !h.outputIncubating:
log.Infof("%T(%x): offering second-layer timeout tx to "+
"sweeper: %v", h, h.htlc.RHash[:],
spew.Sdump(h.htlcResolution.SignedTimeoutTx))
inp := input.MakeHtlcSecondLevelTimeoutAnchorInput(
h.htlcResolution.SignedTimeoutTx,
h.htlcResolution.SignDetails,
h.broadcastHeight,
)
_, err := h.Sweeper.SweepInput(
&inp,
sweep.Params{
Fee: sweep.FeePreference{
ConfTarget: secondLevelConfTarget,
},
},
)
if err != nil {
return nil, err
}
// If we have no SignDetails, and we haven't already sent the output to
// the utxo nursery, then we'll do so now.
case h.htlcResolution.SignDetails == nil && !h.outputIncubating:
log.Tracef("%T(%v): incubating htlc output", h,
h.htlcResolution.ClaimOutpoint)
err := h.IncubateOutputs(
h.ChanPoint, &h.htlcResolution, nil,
h.broadcastHeight,
)
if err != nil {
return nil, err
}
h.outputIncubating = true
if err := h.Checkpoint(h); err != nil {
log.Errorf("unable to Checkpoint: %v", err)
return nil, err
}
}
// Now that we've handed off the HTLC to the nursery or sweeper, we'll
// watch for a spend of the output, and make our next move off of that.
// Depending on if this is our commitment, or the remote party's
// commitment, we'll be watching a different outpoint and script.
outpointToWatch, scriptToWatch, err := h.chainDetailsToWatch()
if err != nil {
return nil, err
}
log.Infof("%T(%v): waiting for HTLC output %v to be spent"+
"fully confirmed", h, h.htlcResolution.ClaimOutpoint,
outpointToWatch)
// We'll block here until either we exit, or the HTLC output on the
// commitment transaction has been spent.
spend, err := waitForSpend(
outpointToWatch, scriptToWatch, h.broadcastHeight,
h.Notifier, h.quit,
)
if err != nil {
return nil, err
}
// If this was the second level transaction published by the sweeper,
// we can checkpoint the resolver now that it's confirmed.
if h.htlcResolution.SignDetails != nil && !h.outputIncubating {
h.outputIncubating = true
if err := h.Checkpoint(h); err != nil {
log.Errorf("unable to Checkpoint: %v", err)
return nil, err
}
}
return spend, err
}
// handleCommitSpend handles the spend of the HTLC output on the commitment
// transaction. If this was our local commitment, the spend will be he
// confirmed second-level timeout transaction, and we'll sweep that into our
// wallet. If the was a remote commitment, the resolver will resolve
// immetiately.
func (h *htlcTimeoutResolver) handleCommitSpend(
commitSpend *chainntnfs.SpendDetail) (ContractResolver, error) {
var (
// claimOutpoint will be the outpoint of the second level
// transaction, or on the remote commitment directly. It will
// start out as set in the resolution, but we'll update it if
// the second-level goes through the sweeper and changes its
// txid.
claimOutpoint = h.htlcResolution.ClaimOutpoint
// spendTxID will be the ultimate spend of the claimOutpoint.
// We set it to the commit spend for now, as this is the
// ultimate spend in case this is a remote commitment. If we go
// through the second-level transaction, we'll update this
// accordingly.
spendTxID = commitSpend.SpenderTxHash
reports []*channeldb.ResolverReport
)
switch {
// If the sweeper is handling the second level transaction, wait for
// the CSV and possible CLTV lock to expire, before sweeping the output
// on the second-level.
case h.htlcResolution.SignDetails != nil:
waitHeight := uint32(commitSpend.SpendingHeight) +
h.htlcResolution.CsvDelay - 1
if h.hasCLTV() {
waitHeight = uint32(math.Max(
float64(waitHeight), float64(h.leaseExpiry),
))
}
h.reportLock.Lock()
h.currentReport.Stage = 2
h.currentReport.MaturityHeight = waitHeight
h.reportLock.Unlock()
if h.hasCLTV() {
log.Infof("%T(%x): waiting for CSV and CLTV lock to "+
"expire at height %v", h, h.htlc.RHash[:],
waitHeight)
} else {
log.Infof("%T(%x): waiting for CSV lock to expire at "+
"height %v", h, h.htlc.RHash[:], waitHeight)
}
err := waitForHeight(waitHeight, h.Notifier, h.quit)
if err != nil {
return nil, err
}
// We'll use this input index to determine the second-level
// output index on the transaction, as the signatures requires
// the indexes to be the same. We don't look for the
// second-level output script directly, as there might be more
// than one HTLC output to the same pkScript.
op := &wire.OutPoint{
Hash: *commitSpend.SpenderTxHash,
Index: commitSpend.SpenderInputIndex,
}
// Let the sweeper sweep the second-level output now that the
// CSV/CLTV locks have expired.
var inp *input.BaseInput
if h.hasCLTV() {
log.Infof("%T(%x): CSV and CLTV locks expired, offering "+
"second-layer output to sweeper: %v", h,
h.htlc.RHash[:], op)
inp = input.NewCsvInputWithCltv(
op, input.LeaseHtlcOfferedTimeoutSecondLevel,
&h.htlcResolution.SweepSignDesc,
h.broadcastHeight, h.htlcResolution.CsvDelay,
h.leaseExpiry,
)
} else {
log.Infof("%T(%x): CSV lock expired, offering "+
"second-layer output to sweeper: %v", h,
h.htlc.RHash[:], op)
inp = input.NewCsvInput(
op, input.HtlcOfferedTimeoutSecondLevel,
&h.htlcResolution.SweepSignDesc,
h.broadcastHeight, h.htlcResolution.CsvDelay,
)
}
_, err = h.Sweeper.SweepInput(
inp,
sweep.Params{
Fee: sweep.FeePreference{
ConfTarget: sweepConfTarget,
},
},
)
if err != nil {
return nil, err
}
// Update the claim outpoint to point to the second-level
// transaction created by the sweeper.
claimOutpoint = *op
fallthrough
// Finally, if this was an output on our commitment transaction, we'll
// wait for the second-level HTLC output to be spent, and for that
// transaction itself to confirm.
case h.htlcResolution.SignedTimeoutTx != nil:
log.Infof("%T(%v): waiting for nursery/sweeper to spend CSV "+
"delayed output", h, claimOutpoint)
sweep, err := waitForSpend(
&claimOutpoint,
h.htlcResolution.SweepSignDesc.Output.PkScript,
h.broadcastHeight, h.Notifier, h.quit,
)
if err != nil {
return nil, err
}
// Update the spend txid to the hash of the sweep transaction.
spendTxID = sweep.SpenderTxHash
// Once our sweep of the timeout tx has confirmed, we add a
// resolution for our timeoutTx tx first stage transaction.
timeoutTx := commitSpend.SpendingTx
index := commitSpend.SpenderInputIndex
spendHash := commitSpend.SpenderTxHash
reports = append(reports, &channeldb.ResolverReport{
OutPoint: timeoutTx.TxIn[index].PreviousOutPoint,
Amount: h.htlc.Amt.ToSatoshis(),
ResolverType: channeldb.ResolverTypeOutgoingHtlc,
ResolverOutcome: channeldb.ResolverOutcomeFirstStage,
SpendTxID: spendHash,
})
}
// With the clean up message sent, we'll now mark the contract
// resolved, update the recovered balance, record the timeout and the
// sweep txid on disk, and wait.
h.resolved = true
h.reportLock.Lock()
h.currentReport.RecoveredBalance = h.currentReport.LimboBalance
h.currentReport.LimboBalance = 0
h.reportLock.Unlock()
amt := btcutil.Amount(h.htlcResolution.SweepSignDesc.Output.Value)
reports = append(reports, &channeldb.ResolverReport{
OutPoint: claimOutpoint,
Amount: amt,
ResolverType: channeldb.ResolverTypeOutgoingHtlc,
ResolverOutcome: channeldb.ResolverOutcomeTimeout,
SpendTxID: spendTxID,
})
return nil, h.Checkpoint(h, reports...)
}
// Stop signals the resolver to cancel any current resolution processes, and
// suspend.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcTimeoutResolver) Stop() {
close(h.quit)
}
// IsResolved returns true if the stored state in the resolve is fully
// resolved. In this case the target output can be forgotten.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcTimeoutResolver) IsResolved() bool {
return h.resolved
}
// report returns a report on the resolution state of the contract.
func (h *htlcTimeoutResolver) report() *ContractReport {
// If the sign details are nil, the report will be created by handled
// by the nursery.
if h.htlcResolution.SignDetails == nil {
return nil
}
h.reportLock.Lock()
defer h.reportLock.Unlock()
copy := h.currentReport
return ©
}
func (h *htlcTimeoutResolver) initReport() {
// We create the initial report. This will only be reported for
// resolvers not handled by the nursery.
finalAmt := h.htlc.Amt.ToSatoshis()
if h.htlcResolution.SignedTimeoutTx != nil {
finalAmt = btcutil.Amount(
h.htlcResolution.SignedTimeoutTx.TxOut[0].Value,
)
}
h.currentReport = ContractReport{
Outpoint: h.htlcResolution.ClaimOutpoint,
Type: ReportOutputOutgoingHtlc,
Amount: finalAmt,
MaturityHeight: h.htlcResolution.Expiry,
LimboBalance: finalAmt,
Stage: 1,
}
}
// Encode writes an encoded version of the ContractResolver into the passed
// Writer.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcTimeoutResolver) Encode(w io.Writer) error {
// First, we'll write out the relevant fields of the
// OutgoingHtlcResolution to the writer.
if err := encodeOutgoingResolution(w, &h.htlcResolution); err != nil {
return err
}
// With that portion written, we can now write out the fields specific
// to the resolver itself.
if err := binary.Write(w, endian, h.outputIncubating); err != nil {
return err
}
if err := binary.Write(w, endian, h.resolved); err != nil {
return err
}
if err := binary.Write(w, endian, h.broadcastHeight); err != nil {
return err
}
if err := binary.Write(w, endian, h.htlc.HtlcIndex); err != nil {
return err
}
// We encode the sign details last for backwards compatibility.
err := encodeSignDetails(w, h.htlcResolution.SignDetails)
if err != nil {
return err
}
return nil
}
// newTimeoutResolverFromReader attempts to decode an encoded ContractResolver
// from the passed Reader instance, returning an active ContractResolver
// instance.
func newTimeoutResolverFromReader(r io.Reader, resCfg ResolverConfig) (
*htlcTimeoutResolver, error) {
h := &htlcTimeoutResolver{
contractResolverKit: *newContractResolverKit(resCfg),
}
// First, we'll read out all the mandatory fields of the
// OutgoingHtlcResolution that we store.
if err := decodeOutgoingResolution(r, &h.htlcResolution); err != nil {
return nil, err
}
// With those fields read, we can now read back the fields that are
// specific to the resolver itself.
if err := binary.Read(r, endian, &h.outputIncubating); err != nil {
return nil, err
}
if err := binary.Read(r, endian, &h.resolved); err != nil {
return nil, err
}
if err := binary.Read(r, endian, &h.broadcastHeight); err != nil {
return nil, err
}
if err := binary.Read(r, endian, &h.htlc.HtlcIndex); err != nil {
return nil, err
}
// Sign details is a new field that was added to the htlc resolution,
// so it is serialized last for backwards compatibility. We try to read
// it, but don't error out if there are not bytes left.
signDetails, err := decodeSignDetails(r)
if err == nil {
h.htlcResolution.SignDetails = signDetails
} else if err != io.EOF && err != io.ErrUnexpectedEOF {
return nil, err
}
h.initReport()
return h, nil
}
// Supplement adds additional information to the resolver that is required
// before Resolve() is called.
//
// NOTE: Part of the htlcContractResolver interface.
func (h *htlcTimeoutResolver) Supplement(htlc channeldb.HTLC) {
h.htlc = htlc
}
// SupplementState allows the user of a ContractResolver to supplement it with
// state required for the proper resolution of a contract.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcTimeoutResolver) SupplementState(state *channeldb.OpenChannel) {
if state.ChanType.HasLeaseExpiration() {
h.leaseExpiry = state.ThawHeight
}
h.channelInitiator = state.IsInitiator
}
// hasCLTV denotes whether the resolver must wait for an additional CLTV to
// expire before resolving the contract.
func (h *htlcTimeoutResolver) hasCLTV() bool {
return h.channelInitiator && h.leaseExpiry > 0
}
// HtlcPoint returns the htlc's outpoint on the commitment tx.
//
// NOTE: Part of the htlcContractResolver interface.
func (h *htlcTimeoutResolver) HtlcPoint() wire.OutPoint {
return h.htlcResolution.HtlcPoint()
}
// A compile time assertion to ensure htlcTimeoutResolver meets the
// ContractResolver interface.
var _ htlcContractResolver = (*htlcTimeoutResolver)(nil)