-
Notifications
You must be signed in to change notification settings - Fork 1.2k
/
rand.go
202 lines (162 loc) · 5.73 KB
/
rand.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
package rand
import (
"context"
"encoding/binary"
logging "github.com/ipfs/go-log/v2"
"github.com/filecoin-project/lotus/chain/beacon"
"github.com/ipfs/go-cid"
"github.com/minio/blake2b-simd"
"go.opencensus.io/trace"
"golang.org/x/xerrors"
"github.com/filecoin-project/go-state-types/abi"
"github.com/filecoin-project/go-state-types/crypto"
"github.com/filecoin-project/lotus/chain/store"
"github.com/filecoin-project/lotus/chain/types"
"github.com/filecoin-project/lotus/chain/vm"
)
var log = logging.Logger("rand")
func DrawRandomness(rbase []byte, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error) {
h := blake2b.New256()
if err := binary.Write(h, binary.BigEndian, int64(pers)); err != nil {
return nil, xerrors.Errorf("deriving randomness: %w", err)
}
VRFDigest := blake2b.Sum256(rbase)
_, err := h.Write(VRFDigest[:])
if err != nil {
return nil, xerrors.Errorf("hashing VRFDigest: %w", err)
}
if err := binary.Write(h, binary.BigEndian, round); err != nil {
return nil, xerrors.Errorf("deriving randomness: %w", err)
}
_, err = h.Write(entropy)
if err != nil {
return nil, xerrors.Errorf("hashing entropy: %w", err)
}
return h.Sum(nil), nil
}
func (sr *stateRand) GetBeaconRandomnessTipset(ctx context.Context, round abi.ChainEpoch, lookback bool) (*types.TipSet, error) {
_, span := trace.StartSpan(ctx, "store.GetBeaconRandomness")
defer span.End()
span.AddAttributes(trace.Int64Attribute("round", int64(round)))
ts, err := sr.cs.LoadTipSet(types.NewTipSetKey(sr.blks...))
if err != nil {
return nil, err
}
if round > ts.Height() {
return nil, xerrors.Errorf("cannot draw randomness from the future")
}
searchHeight := round
if searchHeight < 0 {
searchHeight = 0
}
randTs, err := sr.cs.GetTipsetByHeight(ctx, searchHeight, ts, lookback)
if err != nil {
return nil, err
}
return randTs, nil
}
func (sr *stateRand) GetChainRandomness(ctx context.Context, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte, lookback bool) ([]byte, error) {
_, span := trace.StartSpan(ctx, "store.GetChainRandomness")
defer span.End()
span.AddAttributes(trace.Int64Attribute("round", int64(round)))
ts, err := sr.cs.LoadTipSet(types.NewTipSetKey(sr.blks...))
if err != nil {
return nil, err
}
if round > ts.Height() {
return nil, xerrors.Errorf("cannot draw randomness from the future")
}
searchHeight := round
if searchHeight < 0 {
searchHeight = 0
}
randTs, err := sr.cs.GetTipsetByHeight(ctx, searchHeight, ts, lookback)
if err != nil {
return nil, err
}
mtb := randTs.MinTicketBlock()
// if at (or just past -- for null epochs) appropriate epoch
// or at genesis (works for negative epochs)
return DrawRandomness(mtb.Ticket.VRFProof, pers, round, entropy)
}
type stateRand struct {
cs *store.ChainStore
blks []cid.Cid
beacon beacon.Schedule
}
func NewStateRand(cs *store.ChainStore, blks []cid.Cid, b beacon.Schedule) vm.Rand {
return &stateRand{
cs: cs,
blks: blks,
beacon: b,
}
}
// network v0-12
func (sr *stateRand) GetChainRandomnessV1(ctx context.Context, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error) {
return sr.GetChainRandomness(ctx, pers, round, entropy, true)
}
// network v13 and on
func (sr *stateRand) GetChainRandomnessV2(ctx context.Context, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error) {
return sr.GetChainRandomness(ctx, pers, round, entropy, false)
}
// network v0-12
func (sr *stateRand) GetBeaconRandomnessV1(ctx context.Context, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error) {
randTs, err := sr.GetBeaconRandomnessTipset(ctx, round, true)
if err != nil {
return nil, err
}
be, err := sr.cs.GetLatestBeaconEntry(randTs)
if err != nil {
return nil, err
}
// if at (or just past -- for null epochs) appropriate epoch
// or at genesis (works for negative epochs)
return DrawRandomness(be.Data, pers, round, entropy)
}
// network v13
func (sr *stateRand) GetBeaconRandomnessV2(ctx context.Context, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error) {
randTs, err := sr.GetBeaconRandomnessTipset(ctx, round, false)
if err != nil {
return nil, err
}
be, err := sr.cs.GetLatestBeaconEntry(randTs)
if err != nil {
return nil, err
}
// if at (or just past -- for null epochs) appropriate epoch
// or at genesis (works for negative epochs)
return DrawRandomness(be.Data, pers, round, entropy)
}
// network v14 and on
func (sr *stateRand) GetBeaconRandomnessV3(ctx context.Context, pers crypto.DomainSeparationTag, filecoinEpoch abi.ChainEpoch, entropy []byte) ([]byte, error) {
if filecoinEpoch < 0 {
return sr.GetBeaconRandomnessV2(ctx, pers, filecoinEpoch, entropy)
}
be, err := sr.extractBeaconEntryForEpoch(ctx, filecoinEpoch)
if err != nil {
log.Errorf("failed to get beacon entry as expected: %w", err)
return nil, err
}
return DrawRandomness(be.Data, pers, filecoinEpoch, entropy)
}
func (sr *stateRand) extractBeaconEntryForEpoch(ctx context.Context, filecoinEpoch abi.ChainEpoch) (*types.BeaconEntry, error) {
randTs, err := sr.GetBeaconRandomnessTipset(ctx, filecoinEpoch, false)
if err != nil {
return nil, err
}
round := sr.beacon.BeaconForEpoch(filecoinEpoch).MaxBeaconRoundForEpoch(filecoinEpoch)
for i := 0; i < 20; i++ {
cbe := randTs.Blocks()[0].BeaconEntries
for _, v := range cbe {
if v.Round == round {
return &v, nil
}
}
next, err := sr.cs.LoadTipSet(randTs.Parents())
if err != nil {
return nil, xerrors.Errorf("failed to load parents when searching back for beacon entry: %w", err)
}
randTs = next
}
return nil, xerrors.Errorf("didn't find beacon for round %d (epoch %d)", round, filecoinEpoch)
}