forked from adiabat/btcd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
chainio.go
1407 lines (1259 loc) · 49.5 KB
/
chainio.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
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
// Copyright (c) 2015-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package blockchain
import (
"bytes"
"encoding/binary"
"fmt"
"math/big"
"sort"
"github.com/adiabat/btcd/chaincfg/chainhash"
"github.com/adiabat/btcd/database"
"github.com/adiabat/btcd/wire"
"github.com/adiabat/btcutil"
)
var (
// hashIndexBucketName is the name of the db bucket used to house to the
// block hash -> block height index.
hashIndexBucketName = []byte("hashidx")
// heightIndexBucketName is the name of the db bucket used to house to
// the block height -> block hash index.
heightIndexBucketName = []byte("heightidx")
// chainStateKeyName is the name of the db key used to store the best
// chain state.
chainStateKeyName = []byte("chainstate")
// spendJournalBucketName is the name of the db bucket used to house
// transactions outputs that are spent in each block.
spendJournalBucketName = []byte("spendjournal")
// utxoSetBucketName is the name of the db bucket used to house the
// unspent transaction output set.
utxoSetBucketName = []byte("utxoset")
// byteOrder is the preferred byte order used for serializing numeric
// fields for storage in the database.
byteOrder = binary.LittleEndian
)
// errNotInMainChain signifies that a block hash or height that is not in the
// main chain was requested.
type errNotInMainChain string
// Error implements the error interface.
func (e errNotInMainChain) Error() string {
return string(e)
}
// isNotInMainChainErr returns whether or not the passed error is an
// errNotInMainChain error.
func isNotInMainChainErr(err error) bool {
_, ok := err.(errNotInMainChain)
return ok
}
// errDeserialize signifies that a problem was encountered when deserializing
// data.
type errDeserialize string
// Error implements the error interface.
func (e errDeserialize) Error() string {
return string(e)
}
// isDeserializeErr returns whether or not the passed error is an errDeserialize
// error.
func isDeserializeErr(err error) bool {
_, ok := err.(errDeserialize)
return ok
}
// -----------------------------------------------------------------------------
// The transaction spend journal consists of an entry for each block connected
// to the main chain which contains the transaction outputs the block spends
// serialized such that the order is the reverse of the order they were spent.
//
// This is required because reorganizing the chain necessarily entails
// disconnecting blocks to get back to the point of the fork which implies
// unspending all of the transaction outputs that each block previously spent.
// Since the utxo set, by definition, only contains unspent transaction outputs,
// the spent transaction outputs must be resurrected from somewhere. There is
// more than one way this could be done, however this is the most straight
// forward method that does not require having a transaction index and unpruned
// blockchain.
//
// NOTE: This format is NOT self describing. The additional details such as
// the number of entries (transaction inputs) are expected to come from the
// block itself and the utxo set. The rationale in doing this is to save a
// significant amount of space. This is also the reason the spent outputs are
// serialized in the reverse order they are spent because later transactions
// are allowed to spend outputs from earlier ones in the same block.
//
// The serialized format is:
//
// [<header code><version><compressed txout>],...
//
// Field Type Size
// header code VLQ variable
// version VLQ variable
// compressed txout
// compressed amount VLQ variable
// compressed script []byte variable
//
// The serialized header code format is:
// bit 0 - containing transaction is a coinbase
// bits 1-x - height of the block that contains the spent txout
//
// NOTE: The header code and version are only encoded when the spent txout was
// the final unspent output of the containing transaction. Otherwise, the
// header code will be 0 and the version is not serialized at all. This is
// done because that information is only needed when the utxo set no longer
// has it.
//
// Example 1:
// From block 170 in main blockchain.
//
// 1301320511db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5c
// <><><------------------------------------------------------------------>
// | | |
// | version compressed txout
// header code
//
// - header code: 0x13 (coinbase, height 9)
// - transaction version: 1
// - compressed txout 0:
// - 0x32: VLQ-encoded compressed amount for 5000000000 (50 BTC)
// - 0x05: special script type pay-to-pubkey
// - 0x11...5c: x-coordinate of the pubkey
//
// Example 2:
// Adapted from block 100025 in main blockchain.
//
// 0091f20f006edbc6c4d31bae9f1ccc38538a114bf42de65e868b99700186c64700b2fb57eadf61e106a100a7445a8c3f67898841ec
// <><----------------------------------------------><----><><---------------------------------------------->
// | | | | |
// | compressed txout | version compressed txout
// header code header code
//
// - Last spent output:
// - header code: 0x00 (was not the final unspent output for containing tx)
// - transaction version: Nothing since header code is 0
// - compressed txout:
// - 0x91f20f: VLQ-encoded compressed amount for 34405000000 (344.05 BTC)
// - 0x00: special script type pay-to-pubkey-hash
// - 0x6e...86: pubkey hash
// - Second to last spent output:
// - header code: 0x8b9970 (not coinbase, height 100024)
// - transaction version: 1
// - compressed txout:
// - 0x86c647: VLQ-encoded compressed amount for 13761000000 (137.61 BTC)
// - 0x00: special script type pay-to-pubkey-hash
// - 0xb2...ec: pubkey hash
// -----------------------------------------------------------------------------
// spentTxOut contains a spent transaction output and potentially additional
// contextual information such as whether or not it was contained in a coinbase
// transaction, the version of the transaction it was contained in, and which
// block height the containing transaction was included in. As described in
// the comments above, the additional contextual information will only be valid
// when this spent txout is spending the last unspent output of the containing
// transaction.
type spentTxOut struct {
compressed bool // The amount and public key script are compressed.
version int32 // The version of creating tx.
amount int64 // The amount of the output.
pkScript []byte // The public key script for the output.
// These fields are only set when this is spending the final output of
// the creating tx.
height int32 // Height of the the block containing the creating tx.
isCoinBase bool // Whether creating tx is a coinbase.
}
// spentTxOutHeaderCode returns the calculated header code to be used when
// serializing the provided stxo entry.
func spentTxOutHeaderCode(stxo *spentTxOut) uint64 {
// The header code is 0 when there is no height set for the stxo.
if stxo.height == 0 {
return 0
}
// As described in the serialization format comments, the header code
// encodes the height shifted over one bit and the coinbase flag in the
// lowest bit.
headerCode := uint64(stxo.height) << 1
if stxo.isCoinBase {
headerCode |= 0x01
}
return headerCode
}
// spentTxOutSerializeSize returns the number of bytes it would take to
// serialize the passed stxo according to the format described above.
func spentTxOutSerializeSize(stxo *spentTxOut) int {
headerCode := spentTxOutHeaderCode(stxo)
size := serializeSizeVLQ(headerCode)
if headerCode != 0 {
size += serializeSizeVLQ(uint64(stxo.version))
}
return size + compressedTxOutSize(uint64(stxo.amount), stxo.pkScript,
stxo.version, stxo.compressed)
}
// putSpentTxOut serializes the passed stxo according to the format described
// above directly into the passed target byte slice. The target byte slice must
// be at least large enough to handle the number of bytes returned by the
// spentTxOutSerializeSize function or it will panic.
func putSpentTxOut(target []byte, stxo *spentTxOut) int {
headerCode := spentTxOutHeaderCode(stxo)
offset := putVLQ(target, headerCode)
if headerCode != 0 {
offset += putVLQ(target[offset:], uint64(stxo.version))
}
return offset + putCompressedTxOut(target[offset:], uint64(stxo.amount),
stxo.pkScript, stxo.version, stxo.compressed)
}
// decodeSpentTxOut decodes the passed serialized stxo entry, possibly followed
// by other data, into the passed stxo struct. It returns the number of bytes
// read.
//
// Since the serialized stxo entry does not contain the height, version, or
// coinbase flag of the containing transaction when it still has utxos, the
// caller is responsible for passing in the containing transaction version in
// that case. The provided version is ignore when it is serialized as a part of
// the stxo.
//
// An error will be returned if the version is not serialized as a part of the
// stxo and is also not provided to the function.
func decodeSpentTxOut(serialized []byte, stxo *spentTxOut, txVersion int32) (int, error) {
// Ensure there are bytes to decode.
if len(serialized) == 0 {
return 0, errDeserialize("no serialized bytes")
}
// Deserialize the header code.
code, offset := deserializeVLQ(serialized)
if offset >= len(serialized) {
return offset, errDeserialize("unexpected end of data after " +
"header code")
}
// Decode the header code and deserialize the containing transaction
// version if needed.
//
// Bit 0 indicates containing transaction is a coinbase.
// Bits 1-x encode height of containing transaction.
if code != 0 {
version, bytesRead := deserializeVLQ(serialized[offset:])
offset += bytesRead
if offset >= len(serialized) {
return offset, errDeserialize("unexpected end of data " +
"after version")
}
stxo.isCoinBase = code&0x01 != 0
stxo.height = int32(code >> 1)
stxo.version = int32(version)
} else {
// Ensure a tx version was specified if the stxo did not encode
// it. This should never happen unless there is database
// corruption or this function is being called without the
// proper state.
if txVersion == 0 {
return offset, AssertError("decodeSpentTxOut called " +
"without a containing tx version when the " +
"serialized stxo that does not encode the " +
"version")
}
stxo.version = txVersion
}
// Decode the compressed txout.
compAmount, compScript, bytesRead, err := decodeCompressedTxOut(
serialized[offset:], stxo.version)
offset += bytesRead
if err != nil {
return offset, errDeserialize(fmt.Sprintf("unable to decode "+
"txout: %v", err))
}
stxo.amount = int64(compAmount)
stxo.pkScript = compScript
stxo.compressed = true
return offset, nil
}
// deserializeSpendJournalEntry decodes the passed serialized byte slice into a
// slice of spent txouts according to the format described in detail above.
//
// Since the serialization format is not self describing, as noted in the
// format comments, this function also requires the transactions that spend the
// txouts and a utxo view that contains any remaining existing utxos in the
// transactions referenced by the inputs to the passed transasctions.
func deserializeSpendJournalEntry(serialized []byte, txns []*wire.MsgTx, view *UtxoViewpoint) ([]spentTxOut, error) {
// Calculate the total number of stxos.
var numStxos int
for _, tx := range txns {
numStxos += len(tx.TxIn)
}
// When a block has no spent txouts there is nothing to serialize.
if len(serialized) == 0 {
// Ensure the block actually has no stxos. This should never
// happen unless there is database corruption or an empty entry
// erroneously made its way into the database.
if numStxos != 0 {
return nil, AssertError(fmt.Sprintf("mismatched spend "+
"journal serialization - no serialization for "+
"expected %d stxos", numStxos))
}
return nil, nil
}
// Loop backwards through all transactions so everything is read in
// reverse order to match the serialization order.
stxoIdx := numStxos - 1
stxoInFlight := make(map[chainhash.Hash]int)
offset := 0
stxos := make([]spentTxOut, numStxos)
for txIdx := len(txns) - 1; txIdx > -1; txIdx-- {
tx := txns[txIdx]
// Loop backwards through all of the transaction inputs and read
// the associated stxo.
for txInIdx := len(tx.TxIn) - 1; txInIdx > -1; txInIdx-- {
txIn := tx.TxIn[txInIdx]
stxo := &stxos[stxoIdx]
stxoIdx--
// Get the transaction version for the stxo based on
// whether or not it should be serialized as a part of
// the stxo. Recall that it is only serialized when the
// stxo spends the final utxo of a transaction. Since
// they are deserialized in reverse order, this means
// the first time an entry for a given containing tx is
// encountered that is not already in the utxo view it
// must have been the final spend and thus the extra
// data will be serialized with the stxo. Otherwise,
// the version must be pulled from the utxo entry.
//
// Since the view is not actually modified as the stxos
// are read here and it's possible later entries
// reference earlier ones, an inflight map is maintained
// to detect this case and pull the tx version from the
// entry that contains the version information as just
// described.
var txVersion int32
originHash := &txIn.PreviousOutPoint.Hash
entry := view.LookupEntry(originHash)
if entry != nil {
txVersion = entry.Version()
} else if idx, ok := stxoInFlight[*originHash]; ok {
txVersion = stxos[idx].version
} else {
stxoInFlight[*originHash] = stxoIdx + 1
}
n, err := decodeSpentTxOut(serialized[offset:], stxo,
txVersion)
offset += n
if err != nil {
return nil, errDeserialize(fmt.Sprintf("unable "+
"to decode stxo for %v: %v",
txIn.PreviousOutPoint, err))
}
}
}
return stxos, nil
}
// serializeSpendJournalEntry serializes all of the passed spent txouts into a
// single byte slice according to the format described in detail above.
func serializeSpendJournalEntry(stxos []spentTxOut) []byte {
if len(stxos) == 0 {
return nil
}
// Calculate the size needed to serialize the entire journal entry.
var size int
for i := range stxos {
size += spentTxOutSerializeSize(&stxos[i])
}
serialized := make([]byte, size)
// Serialize each individual stxo directly into the slice in reverse
// order one after the other.
var offset int
for i := len(stxos) - 1; i > -1; i-- {
offset += putSpentTxOut(serialized[offset:], &stxos[i])
}
return serialized
}
// dbFetchSpendJournalEntry fetches the spend journal entry for the passed
// block and deserializes it into a slice of spent txout entries. The provided
// view MUST have the utxos referenced by all of the transactions available for
// the passed block since that information is required to reconstruct the spent
// txouts.
func dbFetchSpendJournalEntry(dbTx database.Tx, block *btcutil.Block, view *UtxoViewpoint) ([]spentTxOut, error) {
// Exclude the coinbase transaction since it can't spend anything.
spendBucket := dbTx.Metadata().Bucket(spendJournalBucketName)
serialized := spendBucket.Get(block.Hash()[:])
blockTxns := block.MsgBlock().Transactions[1:]
stxos, err := deserializeSpendJournalEntry(serialized, blockTxns, view)
if err != nil {
// Ensure any deserialization errors are returned as database
// corruption errors.
if isDeserializeErr(err) {
return nil, database.Error{
ErrorCode: database.ErrCorruption,
Description: fmt.Sprintf("corrupt spend "+
"information for %v: %v", block.Hash(),
err),
}
}
return nil, err
}
return stxos, nil
}
// dbPutSpendJournalEntry uses an existing database transaction to update the
// spend journal entry for the given block hash using the provided slice of
// spent txouts. The spent txouts slice must contain an entry for every txout
// the transactions in the block spend in the order they are spent.
func dbPutSpendJournalEntry(dbTx database.Tx, blockHash *chainhash.Hash, stxos []spentTxOut) error {
spendBucket := dbTx.Metadata().Bucket(spendJournalBucketName)
serialized := serializeSpendJournalEntry(stxos)
return spendBucket.Put(blockHash[:], serialized)
}
// dbRemoveSpendJournalEntry uses an existing database transaction to remove the
// spend journal entry for the passed block hash.
func dbRemoveSpendJournalEntry(dbTx database.Tx, blockHash *chainhash.Hash) error {
spendBucket := dbTx.Metadata().Bucket(spendJournalBucketName)
return spendBucket.Delete(blockHash[:])
}
// -----------------------------------------------------------------------------
// The unspent transaction output (utxo) set consists of an entry for each
// transaction which contains a utxo serialized using a format that is highly
// optimized to reduce space using domain specific compression algorithms. This
// format is a slightly modified version of the format used in Bitcoin Core.
//
// The serialized format is:
//
// <version><height><header code><unspentness bitmap>[<compressed txouts>,...]
//
// Field Type Size
// version VLQ variable
// block height VLQ variable
// header code VLQ variable
// unspentness bitmap []byte variable
// compressed txouts
// compressed amount VLQ variable
// compressed script []byte variable
//
// The serialized header code format is:
// bit 0 - containing transaction is a coinbase
// bit 1 - output zero is unspent
// bit 2 - output one is unspent
// bits 3-x - number of bytes in unspentness bitmap. When both bits 1 and 2
// are unset, it encodes N-1 since there must be at least one unspent
// output.
//
// The rationale for the header code scheme is as follows:
// - Transactions which only pay to a single output and a change output are
// extremely common, thus an extra byte for the unspentness bitmap can be
// avoided for them by encoding those two outputs in the low order bits.
// - Given it is encoded as a VLQ which can encode values up to 127 with a
// single byte, that leaves 4 bits to represent the number of bytes in the
// unspentness bitmap while still only consuming a single byte for the
// header code. In other words, an unspentness bitmap with up to 120
// transaction outputs can be encoded with a single-byte header code.
// This covers the vast majority of transactions.
// - Encoding N-1 bytes when both bits 1 and 2 are unset allows an additional
// 8 outpoints to be encoded before causing the header code to require an
// additional byte.
//
// Example 1:
// From tx in main blockchain:
// Blk 1, 0e3e2357e806b6cdb1f70b54c3a3a17b6714ee1f0e68bebb44a74b1efd512098
//
// 010103320496b538e853519c726a2c91e61ec11600ae1390813a627c66fb8be7947be63c52
// <><><><------------------------------------------------------------------>
// | | \--------\ |
// | height | compressed txout 0
// version header code
//
// - version: 1
// - height: 1
// - header code: 0x03 (coinbase, output zero unspent, 0 bytes of unspentness)
// - unspentness: Nothing since it is zero bytes
// - compressed txout 0:
// - 0x32: VLQ-encoded compressed amount for 5000000000 (50 BTC)
// - 0x04: special script type pay-to-pubkey
// - 0x96...52: x-coordinate of the pubkey
//
// Example 2:
// From tx in main blockchain:
// Blk 113931, 4a16969aa4764dd7507fc1de7f0baa4850a246de90c45e59a3207f9a26b5036f
//
// 0185f90b0a011200e2ccd6ec7c6e2e581349c77e067385fa8236bf8a800900b8025be1b3efc63b0ad48e7f9f10e87544528d58
// <><----><><><------------------------------------------><-------------------------------------------->
// | | | \-------------------\ | |
// version | \--------\ unspentness | compressed txout 2
// height header code compressed txout 0
//
// - version: 1
// - height: 113931
// - header code: 0x0a (output zero unspent, 1 byte in unspentness bitmap)
// - unspentness: [0x01] (bit 0 is set, so output 0+2 = 2 is unspent)
// NOTE: It's +2 since the first two outputs are encoded in the header code
// - compressed txout 0:
// - 0x12: VLQ-encoded compressed amount for 20000000 (0.2 BTC)
// - 0x00: special script type pay-to-pubkey-hash
// - 0xe2...8a: pubkey hash
// - compressed txout 2:
// - 0x8009: VLQ-encoded compressed amount for 15000000 (0.15 BTC)
// - 0x00: special script type pay-to-pubkey-hash
// - 0xb8...58: pubkey hash
//
// Example 3:
// From tx in main blockchain:
// Blk 338156, 1b02d1c8cfef60a189017b9a420c682cf4a0028175f2f563209e4ff61c8c3620
//
// 0193d06c100000108ba5b9e763011dd46a006572d820e448e12d2bbb38640bc718e6
// <><----><><----><-------------------------------------------------->
// | | | \-----------------\ |
// version | \--------\ unspentness |
// height header code compressed txout 22
//
// - version: 1
// - height: 338156
// - header code: 0x10 (2+1 = 3 bytes in unspentness bitmap)
// NOTE: It's +1 since neither bit 1 nor 2 are set, so N-1 is encoded.
// - unspentness: [0x00 0x00 0x10] (bit 20 is set, so output 20+2 = 22 is unspent)
// NOTE: It's +2 since the first two outputs are encoded in the header code
// - compressed txout 22:
// - 0x8ba5b9e763: VLQ-encoded compressed amount for 366875659 (3.66875659 BTC)
// - 0x01: special script type pay-to-script-hash
// - 0x1d...e6: script hash
// -----------------------------------------------------------------------------
// utxoEntryHeaderCode returns the calculated header code to be used when
// serializing the provided utxo entry and the number of bytes needed to encode
// the unspentness bitmap.
func utxoEntryHeaderCode(entry *UtxoEntry, highestOutputIndex uint32) (uint64, int, error) {
// The first two outputs are encoded separately, so offset the index
// accordingly to calculate the correct number of bytes needed to encode
// up to the highest unspent output index.
numBitmapBytes := int((highestOutputIndex + 6) / 8)
// As previously described, one less than the number of bytes is encoded
// when both output 0 and 1 are spent because there must be at least one
// unspent output. Adjust the number of bytes to encode accordingly and
// encode the value by shifting it over 3 bits.
output0Unspent := !entry.IsOutputSpent(0)
output1Unspent := !entry.IsOutputSpent(1)
var numBitmapBytesAdjustment int
if !output0Unspent && !output1Unspent {
if numBitmapBytes == 0 {
return 0, 0, AssertError("attempt to serialize utxo " +
"header for fully spent transaction")
}
numBitmapBytesAdjustment = 1
}
headerCode := uint64(numBitmapBytes-numBitmapBytesAdjustment) << 3
// Set the coinbase, output 0, and output 1 bits in the header code
// accordingly.
if entry.isCoinBase {
headerCode |= 0x01 // bit 0
}
if output0Unspent {
headerCode |= 0x02 // bit 1
}
if output1Unspent {
headerCode |= 0x04 // bit 2
}
return headerCode, numBitmapBytes, nil
}
// serializeUtxoEntry returns the entry serialized to a format that is suitable
// for long-term storage. The format is described in detail above.
func serializeUtxoEntry(entry *UtxoEntry) ([]byte, error) {
// Fully spent entries have no serialization.
if entry.IsFullySpent() {
return nil, nil
}
// Determine the output order by sorting the sparse output index keys.
outputOrder := make([]int, 0, len(entry.sparseOutputs))
for outputIndex := range entry.sparseOutputs {
outputOrder = append(outputOrder, int(outputIndex))
}
sort.Ints(outputOrder)
// Encode the header code and determine the number of bytes the
// unspentness bitmap needs.
highIndex := uint32(outputOrder[len(outputOrder)-1])
headerCode, numBitmapBytes, err := utxoEntryHeaderCode(entry, highIndex)
if err != nil {
return nil, err
}
// Calculate the size needed to serialize the entry.
size := serializeSizeVLQ(uint64(entry.version)) +
serializeSizeVLQ(uint64(entry.blockHeight)) +
serializeSizeVLQ(headerCode) + numBitmapBytes
for _, outputIndex := range outputOrder {
out := entry.sparseOutputs[uint32(outputIndex)]
if out.spent {
continue
}
size += compressedTxOutSize(uint64(out.amount), out.pkScript,
entry.version, out.compressed)
}
// Serialize the version, block height of the containing transaction,
// and header code.
serialized := make([]byte, size)
offset := putVLQ(serialized, uint64(entry.version))
offset += putVLQ(serialized[offset:], uint64(entry.blockHeight))
offset += putVLQ(serialized[offset:], headerCode)
// Serialize the unspentness bitmap.
for i := uint32(0); i < uint32(numBitmapBytes); i++ {
unspentBits := byte(0)
for j := uint32(0); j < 8; j++ {
// The first 2 outputs are encoded via the header code,
// so adjust the output index accordingly.
if !entry.IsOutputSpent(2 + i*8 + j) {
unspentBits |= 1 << uint8(j)
}
}
serialized[offset] = unspentBits
offset++
}
// Serialize the compressed unspent transaction outputs. Outputs that
// are already compressed are serialized without modifications.
for _, outputIndex := range outputOrder {
out := entry.sparseOutputs[uint32(outputIndex)]
if out.spent {
continue
}
offset += putCompressedTxOut(serialized[offset:],
uint64(out.amount), out.pkScript, entry.version,
out.compressed)
}
return serialized, nil
}
// deserializeUtxoEntry decodes a utxo entry from the passed serialized byte
// slice into a new UtxoEntry using a format that is suitable for long-term
// storage. The format is described in detail above.
func deserializeUtxoEntry(serialized []byte) (*UtxoEntry, error) {
// Deserialize the version.
version, bytesRead := deserializeVLQ(serialized)
offset := bytesRead
if offset >= len(serialized) {
return nil, errDeserialize("unexpected end of data after version")
}
// Deserialize the block height.
blockHeight, bytesRead := deserializeVLQ(serialized[offset:])
offset += bytesRead
if offset >= len(serialized) {
return nil, errDeserialize("unexpected end of data after height")
}
// Deserialize the header code.
code, bytesRead := deserializeVLQ(serialized[offset:])
offset += bytesRead
if offset >= len(serialized) {
return nil, errDeserialize("unexpected end of data after header")
}
// Decode the header code.
//
// Bit 0 indicates whether the containing transaction is a coinbase.
// Bit 1 indicates output 0 is unspent.
// Bit 2 indicates output 1 is unspent.
// Bits 3-x encodes the number of non-zero unspentness bitmap bytes that
// follow. When both output 0 and 1 are spent, it encodes N-1.
isCoinBase := code&0x01 != 0
output0Unspent := code&0x02 != 0
output1Unspent := code&0x04 != 0
numBitmapBytes := code >> 3
if !output0Unspent && !output1Unspent {
numBitmapBytes++
}
// Ensure there are enough bytes left to deserialize the unspentness
// bitmap.
if uint64(len(serialized[offset:])) < numBitmapBytes {
return nil, errDeserialize("unexpected end of data for " +
"unspentness bitmap")
}
// Create a new utxo entry with the details deserialized above to house
// all of the utxos.
entry := newUtxoEntry(int32(version), isCoinBase, int32(blockHeight))
// Add sparse output for unspent outputs 0 and 1 as needed based on the
// details provided by the header code.
var outputIndexes []uint32
if output0Unspent {
outputIndexes = append(outputIndexes, 0)
}
if output1Unspent {
outputIndexes = append(outputIndexes, 1)
}
// Decode the unspentness bitmap adding a sparse output for each unspent
// output.
for i := uint32(0); i < uint32(numBitmapBytes); i++ {
unspentBits := serialized[offset]
for j := uint32(0); j < 8; j++ {
if unspentBits&0x01 != 0 {
// The first 2 outputs are encoded via the
// header code, so adjust the output number
// accordingly.
outputNum := 2 + i*8 + j
outputIndexes = append(outputIndexes, outputNum)
}
unspentBits >>= 1
}
offset++
}
// Decode and add all of the utxos.
for i, outputIndex := range outputIndexes {
// Decode the next utxo. The script and amount fields of the
// utxo output are left compressed so decompression can be
// avoided on those that are not accessed. This is done since
// it is quite common for a redeeming transaction to only
// reference a single utxo from a referenced transaction.
compAmount, compScript, bytesRead, err := decodeCompressedTxOut(
serialized[offset:], int32(version))
if err != nil {
return nil, errDeserialize(fmt.Sprintf("unable to "+
"decode utxo at index %d: %v", i, err))
}
offset += bytesRead
entry.sparseOutputs[outputIndex] = &utxoOutput{
spent: false,
compressed: true,
pkScript: compScript,
amount: int64(compAmount),
}
}
return entry, nil
}
// dbFetchUtxoEntry uses an existing database transaction to fetch all unspent
// outputs for the provided Bitcoin transaction hash from the utxo set.
//
// When there is no entry for the provided hash, nil will be returned for the
// both the entry and the error.
func dbFetchUtxoEntry(dbTx database.Tx, hash *chainhash.Hash) (*UtxoEntry, error) {
// Fetch the unspent transaction output information for the passed
// transaction hash. Return now when there is no entry.
utxoBucket := dbTx.Metadata().Bucket(utxoSetBucketName)
serializedUtxo := utxoBucket.Get(hash[:])
if serializedUtxo == nil {
return nil, nil
}
// A non-nil zero-length entry means there is an entry in the database
// for a fully spent transaction which should never be the case.
if len(serializedUtxo) == 0 {
return nil, AssertError(fmt.Sprintf("database contains entry "+
"for fully spent tx %v", hash))
}
// Deserialize the utxo entry and return it.
entry, err := deserializeUtxoEntry(serializedUtxo)
if err != nil {
// Ensure any deserialization errors are returned as database
// corruption errors.
if isDeserializeErr(err) {
return nil, database.Error{
ErrorCode: database.ErrCorruption,
Description: fmt.Sprintf("corrupt utxo entry "+
"for %v: %v", hash, err),
}
}
return nil, err
}
return entry, nil
}
// dbPutUtxoView uses an existing database transaction to update the utxo set
// in the database based on the provided utxo view contents and state. In
// particular, only the entries that have been marked as modified are written
// to the database.
func dbPutUtxoView(dbTx database.Tx, view *UtxoViewpoint) error {
utxoBucket := dbTx.Metadata().Bucket(utxoSetBucketName)
for txHashIter, entry := range view.entries {
// No need to update the database if the entry was not modified.
if entry == nil || !entry.modified {
continue
}
// Serialize the utxo entry without any entries that have been
// spent.
serialized, err := serializeUtxoEntry(entry)
if err != nil {
return err
}
// Make a copy of the hash because the iterator changes on each
// loop iteration and thus slicing it directly would cause the
// data to change out from under the put/delete funcs below.
txHash := txHashIter
// Remove the utxo entry if it is now fully spent.
if serialized == nil {
if err := utxoBucket.Delete(txHash[:]); err != nil {
return err
}
continue
}
// At this point the utxo entry is not fully spent, so store its
// serialization in the database.
err = utxoBucket.Put(txHash[:], serialized)
if err != nil {
return err
}
}
return nil
}
// -----------------------------------------------------------------------------
// The block index consists of two buckets with an entry for every block in the
// main chain. One bucket is for the hash to height mapping and the other is
// for the height to hash mapping.
//
// The serialized format for values in the hash to height bucket is:
// <height>
//
// Field Type Size
// height uint32 4 bytes
//
// The serialized format for values in the height to hash bucket is:
// <hash>
//
// Field Type Size
// hash chainhash.Hash chainhash.HashSize
// -----------------------------------------------------------------------------
// dbPutBlockIndex uses an existing database transaction to update or add the
// block index entries for the hash to height and height to hash mappings for
// the provided values.
func dbPutBlockIndex(dbTx database.Tx, hash *chainhash.Hash, height int32) error {
// Serialize the height for use in the index entries.
var serializedHeight [4]byte
byteOrder.PutUint32(serializedHeight[:], uint32(height))
// Add the block hash to height mapping to the index.
meta := dbTx.Metadata()
hashIndex := meta.Bucket(hashIndexBucketName)
if err := hashIndex.Put(hash[:], serializedHeight[:]); err != nil {
return err
}
// Add the block height to hash mapping to the index.
heightIndex := meta.Bucket(heightIndexBucketName)
return heightIndex.Put(serializedHeight[:], hash[:])
}
// dbRemoveBlockIndex uses an existing database transaction remove block index
// entries from the hash to height and height to hash mappings for the provided
// values.
func dbRemoveBlockIndex(dbTx database.Tx, hash *chainhash.Hash, height int32) error {
// Remove the block hash to height mapping.
meta := dbTx.Metadata()
hashIndex := meta.Bucket(hashIndexBucketName)
if err := hashIndex.Delete(hash[:]); err != nil {
return err
}
// Remove the block height to hash mapping.
var serializedHeight [4]byte
byteOrder.PutUint32(serializedHeight[:], uint32(height))
heightIndex := meta.Bucket(heightIndexBucketName)
return heightIndex.Delete(serializedHeight[:])
}
// dbFetchHeightByHash uses an existing database transaction to retrieve the
// height for the provided hash from the index.
func dbFetchHeightByHash(dbTx database.Tx, hash *chainhash.Hash) (int32, error) {
meta := dbTx.Metadata()
hashIndex := meta.Bucket(hashIndexBucketName)
serializedHeight := hashIndex.Get(hash[:])
if serializedHeight == nil {
str := fmt.Sprintf("block %s is not in the main chain", hash)
return 0, errNotInMainChain(str)
}
return int32(byteOrder.Uint32(serializedHeight)), nil
}
// dbFetchHashByHeight uses an existing database transaction to retrieve the
// hash for the provided height from the index.
func dbFetchHashByHeight(dbTx database.Tx, height int32) (*chainhash.Hash, error) {
var serializedHeight [4]byte
byteOrder.PutUint32(serializedHeight[:], uint32(height))
meta := dbTx.Metadata()
heightIndex := meta.Bucket(heightIndexBucketName)
hashBytes := heightIndex.Get(serializedHeight[:])
if hashBytes == nil {
str := fmt.Sprintf("no block at height %d exists", height)
return nil, errNotInMainChain(str)
}
var hash chainhash.Hash
copy(hash[:], hashBytes)
return &hash, nil
}
// -----------------------------------------------------------------------------
// The best chain state consists of the best block hash and height, the total
// number of transactions up to and including those in the best block, and the
// accumulated work sum up to and including the best block.
//
// The serialized format is:
//
// <block hash><block height><total txns><work sum length><work sum>
//
// Field Type Size
// block hash chainhash.Hash chainhash.HashSize
// block height uint32 4 bytes
// total txns uint64 8 bytes
// work sum length uint32 4 bytes
// work sum big.Int work sum length
// -----------------------------------------------------------------------------
// bestChainState represents the data to be stored the database for the current
// best chain state.
type bestChainState struct {
hash chainhash.Hash
height uint32
totalTxns uint64
workSum *big.Int
}
// serializeBestChainState returns the serialization of the passed block best
// chain state. This is data to be stored in the chain state bucket.
func serializeBestChainState(state bestChainState) []byte {
// Calculate the full size needed to serialize the chain state.
workSumBytes := state.workSum.Bytes()
workSumBytesLen := uint32(len(workSumBytes))
serializedLen := chainhash.HashSize + 4 + 8 + 4 + workSumBytesLen
// Serialize the chain state.
serializedData := make([]byte, serializedLen)
copy(serializedData[0:chainhash.HashSize], state.hash[:])
offset := uint32(chainhash.HashSize)
byteOrder.PutUint32(serializedData[offset:], state.height)
offset += 4
byteOrder.PutUint64(serializedData[offset:], state.totalTxns)
offset += 8
byteOrder.PutUint32(serializedData[offset:], workSumBytesLen)
offset += 4
copy(serializedData[offset:], workSumBytes)
return serializedData[:]
}
// deserializeBestChainState deserializes the passed serialized best chain
// state. This is data stored in the chain state bucket and is updated after
// every block is connected or disconnected form the main chain.
// block.
func deserializeBestChainState(serializedData []byte) (bestChainState, error) {
// Ensure the serialized data has enough bytes to properly deserialize
// the hash, height, total transactions, and work sum length.