/
blinded_data.go
304 lines (236 loc) · 7.93 KB
/
blinded_data.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
package record
import (
"bytes"
"encoding/binary"
"io"
"github.com/btcsuite/btcd/btcec/v2"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/tlv"
)
// BlindedRouteData contains the information that is included in a blinded
// route encrypted data blob that is created by the recipient to provide
// forwarding information.
type BlindedRouteData struct {
// ShortChannelID is the channel ID of the next hop.
ShortChannelID tlv.RecordT[tlv.TlvType2, lnwire.ShortChannelID]
// NextBlindingOverride is a blinding point that should be switched
// in for the next hop. This is used to combine two blinded paths into
// one (which primarily is used in onion messaging, but in theory
// could be used for payments as well).
NextBlindingOverride tlv.OptionalRecordT[tlv.TlvType8, *btcec.PublicKey]
// RelayInfo provides the relay parameters for the hop.
RelayInfo tlv.RecordT[tlv.TlvType10, PaymentRelayInfo]
// Constraints provides the payment relay constraints for the hop.
Constraints tlv.OptionalRecordT[tlv.TlvType12, PaymentConstraints]
// Features is the set of features the payment requires.
Features tlv.OptionalRecordT[tlv.TlvType14, lnwire.FeatureVector]
}
// NewBlindedRouteData creates the data that's provided for hops within a
// blinded route.
func NewBlindedRouteData(chanID lnwire.ShortChannelID,
blindingOverride *btcec.PublicKey, relayInfo PaymentRelayInfo,
constraints *PaymentConstraints,
features *lnwire.FeatureVector) *BlindedRouteData {
info := &BlindedRouteData{
ShortChannelID: tlv.NewRecordT[tlv.TlvType2](chanID),
RelayInfo: tlv.NewRecordT[tlv.TlvType10](relayInfo),
}
if blindingOverride != nil {
info.NextBlindingOverride = tlv.SomeRecordT(
tlv.NewPrimitiveRecord[tlv.TlvType8](blindingOverride))
}
if constraints != nil {
info.Constraints = tlv.SomeRecordT(
tlv.NewRecordT[tlv.TlvType12](*constraints))
}
if features != nil {
info.Features = tlv.SomeRecordT(
tlv.NewRecordT[tlv.TlvType14](*features),
)
}
return info
}
// DecodeBlindedRouteData decodes the data provided within a blinded route.
func DecodeBlindedRouteData(r io.Reader) (*BlindedRouteData, error) {
var (
d BlindedRouteData
blindingOverride = d.NextBlindingOverride.Zero()
constraints = d.Constraints.Zero()
features = d.Features.Zero()
)
var tlvRecords lnwire.ExtraOpaqueData
if err := lnwire.ReadElements(r, &tlvRecords); err != nil {
return nil, err
}
typeMap, err := tlvRecords.ExtractRecords(
&d.ShortChannelID,
&blindingOverride, &d.RelayInfo.Val, &constraints,
&features,
)
if err != nil {
return nil, err
}
val, ok := typeMap[d.NextBlindingOverride.TlvType()]
if ok && val == nil {
d.NextBlindingOverride = tlv.SomeRecordT(blindingOverride)
}
if val, ok := typeMap[d.Constraints.TlvType()]; ok && val == nil {
d.Constraints = tlv.SomeRecordT(constraints)
}
if val, ok := typeMap[d.Features.TlvType()]; ok && val == nil {
d.Features = tlv.SomeRecordT(features)
}
return &d, nil
}
// EncodeBlindedRouteData encodes the blinded route data provided.
func EncodeBlindedRouteData(data *BlindedRouteData) ([]byte, error) {
var (
e lnwire.ExtraOpaqueData
recordProducers = make([]tlv.RecordProducer, 0, 5)
)
recordProducers = append(recordProducers, &data.ShortChannelID)
data.NextBlindingOverride.WhenSome(func(pk tlv.RecordT[tlv.TlvType8,
*btcec.PublicKey]) {
recordProducers = append(recordProducers, &pk)
})
recordProducers = append(recordProducers, &data.RelayInfo.Val)
data.Constraints.WhenSome(func(cs tlv.RecordT[tlv.TlvType12,
PaymentConstraints]) {
recordProducers = append(recordProducers, &cs)
})
data.Features.WhenSome(func(f tlv.RecordT[tlv.TlvType14,
lnwire.FeatureVector]) {
recordProducers = append(recordProducers, &f)
})
if err := e.PackRecords(recordProducers...); err != nil {
return nil, err
}
return e[:], nil
}
// PaymentRelayInfo describes the relay policy for a blinded path.
type PaymentRelayInfo struct {
// CltvExpiryDelta is the expiry delta for the payment.
CltvExpiryDelta uint16
// FeeRate is the fee rate that will be charged per millionth of a
// satoshi.
FeeRate uint32
// BaseFee is the per-htlc fee charged.
BaseFee uint32
}
// newPaymentRelayRecord creates a tlv.Record that encodes the payment relay
// (type 10) type for an encrypted blob payload.
func (i *PaymentRelayInfo) Record() tlv.Record {
return tlv.MakeDynamicRecord(
10, &i, func() uint64 {
// uint16 + uint32 + tuint32
return 2 + 4 + tlv.SizeTUint32(i.BaseFee)
}, encodePaymentRelay, decodePaymentRelay,
)
}
func encodePaymentRelay(w io.Writer, val interface{}, buf *[8]byte) error {
if t, ok := val.(**PaymentRelayInfo); ok {
relayInfo := *t
// Just write our first 6 bytes directly.
binary.BigEndian.PutUint16(buf[:2], relayInfo.CltvExpiryDelta)
binary.BigEndian.PutUint32(buf[2:6], relayInfo.FeeRate)
if _, err := w.Write(buf[0:6]); err != nil {
return err
}
// We can safely reuse buf here because we overwrite its
// contents.
return tlv.ETUint32(w, &relayInfo.BaseFee, buf)
}
return tlv.NewTypeForEncodingErr(val, "**hop.PaymentRelayInfo")
}
func decodePaymentRelay(r io.Reader, val interface{}, buf *[8]byte,
l uint64) error {
if t, ok := val.(**PaymentRelayInfo); ok && l <= 10 {
scratch := make([]byte, l)
n, err := io.ReadFull(r, scratch)
if err != nil {
return err
}
// We expect at least 6 bytes, because we have 2 bytes for
// cltv delta and 4 bytes for fee rate.
if n < 6 {
return tlv.NewTypeForDecodingErr(val,
"*hop.paymentRelayInfo", uint64(n), 6)
}
relayInfo := *t
relayInfo.CltvExpiryDelta = binary.BigEndian.Uint16(
scratch[0:2],
)
relayInfo.FeeRate = binary.BigEndian.Uint32(scratch[2:6])
// To be able to re-use the DTUint32 function we create a
// buffer with just the bytes holding the variable length u32.
// If the base fee is zero, this will be an empty buffer, which
// is okay.
b := bytes.NewBuffer(scratch[6:])
return tlv.DTUint32(b, &relayInfo.BaseFee, buf, l-6)
}
return tlv.NewTypeForDecodingErr(val, "*hop.paymentRelayInfo", l, 10)
}
// PaymentConstraints is a set of restrictions on a payment.
type PaymentConstraints struct {
// MaxCltvExpiry is the maximum expiry height for the payment.
MaxCltvExpiry uint32
// HtlcMinimumMsat is the minimum htlc size for the payment.
HtlcMinimumMsat lnwire.MilliSatoshi
}
func (p *PaymentConstraints) Record() tlv.Record {
return tlv.MakeDynamicRecord(
12, &p, func() uint64 {
// uint32 + tuint64.
return 4 + tlv.SizeTUint64(uint64(
p.HtlcMinimumMsat,
))
},
encodePaymentConstraints, decodePaymentConstraints,
)
}
func encodePaymentConstraints(w io.Writer, val interface{},
buf *[8]byte) error {
if c, ok := val.(**PaymentConstraints); ok {
constraints := *c
binary.BigEndian.PutUint32(buf[:4], constraints.MaxCltvExpiry)
if _, err := w.Write(buf[:4]); err != nil {
return err
}
// We can safely re-use buf here because we overwrite its
// contents.
htlcMsat := uint64(constraints.HtlcMinimumMsat)
return tlv.ETUint64(w, &htlcMsat, buf)
}
return tlv.NewTypeForEncodingErr(val, "**PaymentConstraints")
}
func decodePaymentConstraints(r io.Reader, val interface{}, buf *[8]byte,
l uint64) error {
if c, ok := val.(**PaymentConstraints); ok && l <= 12 {
scratch := make([]byte, l)
n, err := io.ReadFull(r, scratch)
if err != nil {
return err
}
// We expect at least 4 bytes for our uint32.
if n < 4 {
return tlv.NewTypeForDecodingErr(val,
"*paymentConstraints", uint64(n), 4)
}
payConstraints := *c
payConstraints.MaxCltvExpiry = binary.BigEndian.Uint32(
scratch[:4],
)
// This could be empty if our minimum is zero, that's okay.
var (
b = bytes.NewBuffer(scratch[4:])
minHtlc uint64
)
err = tlv.DTUint64(b, &minHtlc, buf, l-4)
if err != nil {
return err
}
payConstraints.HtlcMinimumMsat = lnwire.MilliSatoshi(minHtlc)
return nil
}
return tlv.NewTypeForDecodingErr(val, "**PaymentConstraints", l, l)
}