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lightningnetwork / lnd / 17654288916

11 Sep 2025 06:49PM UTC coverage: 66.653% (+0.002%) from 66.651%
17654288916

Pull #9975

github

web-flow
Merge 0f841006c into 5082566ed
Pull Request #9975: Add Support for P2TR Fallback Addresses in BOLT-11

5 of 11 new or added lines in 2 files covered. (45.45%)

58 existing lines in 18 files now uncovered.

136302 of 204494 relevant lines covered (66.65%)

21470.28 hits per line

Source File
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70.53
/zpay32/encode.go
1
package zpay32
2

3
import (
4
        "bytes"
5
        "encoding/binary"
6
        "fmt"
7

8
        "github.com/btcsuite/btcd/btcutil"
9
        "github.com/btcsuite/btcd/btcutil/bech32"
10
        "github.com/btcsuite/btcd/chaincfg"
11
        "github.com/btcsuite/btcd/chaincfg/chainhash"
12
        "github.com/lightningnetwork/lnd/fn/v2"
13
        "github.com/lightningnetwork/lnd/lnwire"
14
)
15

16
// Encode takes the given MessageSigner and returns a string encoding this
17
// invoice signed by the node key of the signer.
18
func (invoice *Invoice) Encode(signer MessageSigner) (string, error) {
185✔
19
        // First check that this invoice is valid before starting the encoding.
185✔
20
        if err := validateInvoice(invoice); err != nil {
188✔
21
                return "", err
3✔
22
        }
3✔
23

24
        // The buffer will encoded the invoice data using 5-bit groups (base32).
25
        var bufferBase32 bytes.Buffer
182✔
26

182✔
27
        // The timestamp will be encoded using 35 bits, in base32.
182✔
28
        timestampBase32 := uint64ToBase32(uint64(invoice.Timestamp.Unix()))
182✔
29

182✔
30
        // The timestamp must be exactly 35 bits, which means 7 groups. If it
182✔
31
        // can fit into fewer groups we add leading zero groups, if it is too
182✔
32
        // big we fail early, as there is not possible to encode it.
182✔
33
        if len(timestampBase32) > timestampBase32Len {
182✔
34
                return "", fmt.Errorf("timestamp too big: %d",
×
35
                        invoice.Timestamp.Unix())
×
36
        }
×
37

38
        // Add zero bytes to the first timestampBase32Len-len(timestampBase32)
39
        // groups, then add the non-zero groups.
40
        zeroes := make([]byte, timestampBase32Len-len(timestampBase32))
182✔
41
        _, err := bufferBase32.Write(zeroes)
182✔
42
        if err != nil {
182✔
43
                return "", fmt.Errorf("unable to write to buffer: %w", err)
×
44
        }
×
45
        _, err = bufferBase32.Write(timestampBase32)
182✔
46
        if err != nil {
182✔
47
                return "", fmt.Errorf("unable to write to buffer: %w", err)
×
48
        }
×
49

50
        // We now write the tagged fields to the buffer, which will fill the
51
        // rest of the data part before the signature.
52
        if err := writeTaggedFields(&bufferBase32, invoice); err != nil {
182✔
53
                return "", err
×
54
        }
×
55

56
        // The human-readable part (hrp) is "ln" + net hrp + optional amount,
57
        // except for signet where we add an additional "s" to differentiate it
58
        // from the older testnet3 (Core devs decided to use the same hrp for
59
        // signet as for testnet3 which is not optimal for LN). See
60
        // https://github.com/lightningnetwork/lightning-rfc/pull/844 for more
61
        // information.
62
        hrp := "ln" + invoice.Net.Bech32HRPSegwit
182✔
63
        if invoice.Net.Name == chaincfg.SigNetParams.Name {
192✔
64
                hrp = "lntbs"
10✔
65
        }
10✔
66
        if invoice.MilliSat != nil {
313✔
67
                // Encode the amount using the fewest possible characters.
131✔
68
                am, err := encodeAmount(*invoice.MilliSat)
131✔
69
                if err != nil {
131✔
70
                        return "", err
×
71
                }
×
72
                hrp += am
131✔
73
        }
74

75
        // The signature is over the single SHA-256 hash of the hrp + the
76
        // tagged fields encoded in base256.
77
        taggedFieldsBytes, err := bech32.ConvertBits(bufferBase32.Bytes(), 5, 8, true)
182✔
78
        if err != nil {
182✔
79
                return "", err
×
80
        }
×
81

82
        toSign := append([]byte(hrp), taggedFieldsBytes...)
182✔
83

182✔
84
        // We use compact signature format, and also encoded the recovery ID
182✔
85
        // such that a reader of the invoice can recover our pubkey from the
182✔
86
        // signature.
182✔
87
        sign, err := signer.SignCompact(toSign)
182✔
88
        if err != nil {
182✔
89
                return "", err
×
90
        }
×
91

92
        // From the header byte we can extract the recovery ID, and the last 64
93
        // bytes encode the signature.
94
        recoveryID := sign[0] - 27 - 4
182✔
95
        sig, err := lnwire.NewSigFromWireECDSA(sign[1:])
182✔
96
        if err != nil {
182✔
97
                return "", err
×
98
        }
×
99

100
        // If the pubkey field was explicitly set, it must be set to the pubkey
101
        // used to create the signature.
102
        if invoice.Destination != nil {
250✔
103
                signature, err := sig.ToSignature()
68✔
104
                if err != nil {
68✔
105
                        return "", fmt.Errorf("unable to deserialize "+
×
106
                                "signature: %v", err)
×
107
                }
×
108

109
                hash := chainhash.HashB(toSign)
68✔
110
                valid := signature.Verify(hash, invoice.Destination)
68✔
111
                if !valid {
125✔
112
                        return "", fmt.Errorf("signature does not match " +
57✔
113
                                "provided pubkey")
57✔
114
                }
57✔
115
        }
116

117
        // Convert the signature to base32 before writing it to the buffer.
118
        signBase32, err := bech32.ConvertBits(
125✔
119
                append(sig.RawBytes(), recoveryID),
125✔
120
                8, 5, true,
125✔
121
        )
125✔
122
        if err != nil {
125✔
123
                return "", err
×
124
        }
×
125
        bufferBase32.Write(signBase32)
125✔
126

125✔
127
        // Now we can create the bech32 encoded string from the base32 buffer.
125✔
128
        b32, err := bech32.Encode(hrp, bufferBase32.Bytes())
125✔
129
        if err != nil {
125✔
130
                return "", err
×
131
        }
×
132

133
        // Before returning, check that the bech32 encoded string is not greater
134
        // than our largest supported invoice size.
135
        if len(b32) > maxInvoiceLength {
125✔
136
                return "", ErrInvoiceTooLarge
×
137
        }
×
138

139
        return b32, nil
125✔
140
}
141

142
// writeTaggedFields writes the non-nil tagged fields of the Invoice to the
143
// base32 buffer.
144
func writeTaggedFields(bufferBase32 *bytes.Buffer, invoice *Invoice) error {
182✔
145
        if invoice.PaymentHash != nil {
364✔
146
                err := writeBytes32(bufferBase32, fieldTypeP, *invoice.PaymentHash)
182✔
147
                if err != nil {
182✔
148
                        return err
×
149
                }
×
150
        }
151

152
        if invoice.Description != nil {
340✔
153
                base32, err := bech32.ConvertBits([]byte(*invoice.Description),
158✔
154
                        8, 5, true)
158✔
155
                if err != nil {
158✔
156
                        return err
×
157
                }
×
158
                err = writeTaggedField(bufferBase32, fieldTypeD, base32)
158✔
159
                if err != nil {
158✔
160
                        return err
×
161
                }
×
162
        }
163

164
        if invoice.DescriptionHash != nil {
206✔
165
                err := writeBytes32(
24✔
166
                        bufferBase32, fieldTypeH, *invoice.DescriptionHash,
24✔
167
                )
24✔
168
                if err != nil {
24✔
169
                        return err
×
170
                }
×
171
        }
172

173
        if invoice.Metadata != nil {
190✔
174
                base32, err := bech32.ConvertBits(invoice.Metadata, 8, 5, true)
8✔
175
                if err != nil {
8✔
176
                        return err
×
177
                }
×
178
                err = writeTaggedField(bufferBase32, fieldTypeM, base32)
8✔
179
                if err != nil {
8✔
180
                        return err
×
181
                }
×
182
        }
183

184
        if invoice.minFinalCLTVExpiry != nil {
196✔
185
                finalDelta := uint64ToBase32(*invoice.minFinalCLTVExpiry)
14✔
186
                err := writeTaggedField(bufferBase32, fieldTypeC, finalDelta)
14✔
187
                if err != nil {
14✔
188
                        return err
×
189
                }
×
190
        }
191

192
        if invoice.expiry != nil {
287✔
193
                seconds := invoice.expiry.Seconds()
105✔
194
                expiry := uint64ToBase32(uint64(seconds))
105✔
195
                err := writeTaggedField(bufferBase32, fieldTypeX, expiry)
105✔
196
                if err != nil {
105✔
197
                        return err
×
198
                }
×
199
        }
200

201
        if invoice.FallbackAddr != nil {
193✔
202
                var version byte
11✔
203
                switch addr := invoice.FallbackAddr.(type) {
11✔
204
                case *btcutil.AddressPubKeyHash:
6✔
205
                        version = 17
6✔
206
                case *btcutil.AddressScriptHash:
2✔
207
                        version = 18
2✔
208
                case *btcutil.AddressWitnessPubKeyHash:
2✔
209
                        version = addr.WitnessVersion()
2✔
210
                case *btcutil.AddressWitnessScriptHash:
1✔
211
                        version = addr.WitnessVersion()
1✔
NEW
212
                case *btcutil.AddressTaproot:
×
NEW
213
                        version = addr.WitnessVersion()
×
214
                default:
×
215
                        return fmt.Errorf("unknown fallback address type")
×
216
                }
217
                base32Addr, err := bech32.ConvertBits(
11✔
218
                        invoice.FallbackAddr.ScriptAddress(), 8, 5, true)
11✔
219
                if err != nil {
11✔
220
                        return err
×
221
                }
×
222

223
                err = writeTaggedField(bufferBase32, fieldTypeF,
11✔
224
                        append([]byte{version}, base32Addr...))
11✔
225
                if err != nil {
11✔
226
                        return err
×
227
                }
×
228
        }
229

230
        for _, routeHint := range invoice.RouteHints {
192✔
231
                // Each hop hint is encoded using 51 bytes, so we'll make to
10✔
232
                // sure to allocate enough space for the whole route hint.
10✔
233
                routeHintBase256 := make([]byte, 0, hopHintLen*len(routeHint))
10✔
234

10✔
235
                for _, hopHint := range routeHint {
24✔
236
                        hopHintBase256 := make([]byte, hopHintLen)
14✔
237
                        copy(hopHintBase256[:33], hopHint.NodeID.SerializeCompressed())
14✔
238
                        binary.BigEndian.PutUint64(
14✔
239
                                hopHintBase256[33:41], hopHint.ChannelID,
14✔
240
                        )
14✔
241
                        binary.BigEndian.PutUint32(
14✔
242
                                hopHintBase256[41:45], hopHint.FeeBaseMSat,
14✔
243
                        )
14✔
244
                        binary.BigEndian.PutUint32(
14✔
245
                                hopHintBase256[45:49], hopHint.FeeProportionalMillionths,
14✔
246
                        )
14✔
247
                        binary.BigEndian.PutUint16(
14✔
248
                                hopHintBase256[49:51], hopHint.CLTVExpiryDelta,
14✔
249
                        )
14✔
250
                        routeHintBase256 = append(routeHintBase256, hopHintBase256...)
14✔
251
                }
14✔
252

253
                routeHintBase32, err := bech32.ConvertBits(
10✔
254
                        routeHintBase256, 8, 5, true,
10✔
255
                )
10✔
256
                if err != nil {
10✔
257
                        return err
×
258
                }
×
259

260
                err = writeTaggedField(bufferBase32, fieldTypeR, routeHintBase32)
10✔
261
                if err != nil {
10✔
262
                        return err
×
263
                }
×
264
        }
265

266
        for _, path := range invoice.BlindedPaymentPaths {
189✔
267
                var buf bytes.Buffer
7✔
268

7✔
269
                err := path.Encode(&buf)
7✔
270
                if err != nil {
7✔
271
                        return err
×
272
                }
×
273

274
                blindedPathBase32, err := bech32.ConvertBits(
7✔
275
                        buf.Bytes(), 8, 5, true,
7✔
276
                )
7✔
277
                if err != nil {
7✔
278
                        return err
×
279
                }
×
280

281
                err = writeTaggedField(
7✔
282
                        bufferBase32, fieldTypeB, blindedPathBase32,
7✔
283
                )
7✔
284
                if err != nil {
7✔
285
                        return err
×
286
                }
×
287
        }
288

289
        if invoice.Destination != nil {
250✔
290
                // Convert 33 byte pubkey to 53 5-bit groups.
68✔
291
                pubKeyBase32, err := bech32.ConvertBits(
68✔
292
                        invoice.Destination.SerializeCompressed(), 8, 5, true)
68✔
293
                if err != nil {
68✔
294
                        return err
×
295
                }
×
296

297
                if len(pubKeyBase32) != pubKeyBase32Len {
68✔
298
                        return fmt.Errorf("invalid pubkey length: %d",
×
299
                                len(invoice.Destination.SerializeCompressed()))
×
300
                }
×
301

302
                err = writeTaggedField(bufferBase32, fieldTypeN, pubKeyBase32)
68✔
303
                if err != nil {
68✔
304
                        return err
×
305
                }
×
306
        }
307

308
        err := fn.MapOptionZ(invoice.PaymentAddr, func(addr [32]byte) error {
285✔
309
                return writeBytes32(bufferBase32, fieldTypeS, addr)
103✔
310
        })
103✔
311
        if err != nil {
182✔
312
                return err
×
313
        }
×
314

315
        if invoice.Features.SerializeSize32() > 0 {
216✔
316
                var b bytes.Buffer
34✔
317
                err := invoice.Features.RawFeatureVector.EncodeBase32(&b)
34✔
318
                if err != nil {
34✔
319
                        return err
×
320
                }
×
321

322
                err = writeTaggedField(bufferBase32, fieldType9, b.Bytes())
34✔
323
                if err != nil {
34✔
324
                        return err
×
325
                }
×
326
        }
327

328
        return nil
182✔
329
}
330

331
// writeBytes32 encodes a 32-byte array as base32 and writes it to bufferBase32
332
// under the passed fieldType.
333
func writeBytes32(bufferBase32 *bytes.Buffer, fieldType byte, b [32]byte) error {
306✔
334
        // Convert 32 byte hash to 52 5-bit groups.
306✔
335
        base32, err := bech32.ConvertBits(b[:], 8, 5, true)
306✔
336
        if err != nil {
306✔
337
                return err
×
338
        }
×
339

340
        return writeTaggedField(bufferBase32, fieldType, base32)
306✔
341
}
342

343
// writeTaggedField takes the type of a tagged data field, and the data of
344
// the tagged field (encoded in base32), and writes the type, length and data
345
// to the buffer.
346
func writeTaggedField(bufferBase32 *bytes.Buffer, dataType byte, data []byte) error {
703✔
347
        // Length must be exactly 10 bits, so add leading zero groups if
703✔
348
        // needed.
703✔
349
        lenBase32 := uint64ToBase32(uint64(len(data)))
703✔
350
        for len(lenBase32) < 2 {
986✔
351
                lenBase32 = append([]byte{0}, lenBase32...)
283✔
352
        }
283✔
353

354
        if len(lenBase32) != 2 {
703✔
355
                return fmt.Errorf("data length too big to fit within 10 bits: %d",
×
356
                        len(data))
×
357
        }
×
358

359
        err := bufferBase32.WriteByte(dataType)
703✔
360
        if err != nil {
703✔
361
                return fmt.Errorf("unable to write to buffer: %w", err)
×
362
        }
×
363
        _, err = bufferBase32.Write(lenBase32)
703✔
364
        if err != nil {
703✔
365
                return fmt.Errorf("unable to write to buffer: %w", err)
×
366
        }
×
367
        _, err = bufferBase32.Write(data)
703✔
368
        if err != nil {
703✔
369
                return fmt.Errorf("unable to write to buffer: %w", err)
×
370
        }
×
371

372
        return nil
703✔
373
}
374

375
// uint64ToBase32 converts a uint64 to a base32 encoded integer encoded using
376
// as few 5-bit groups as possible.
377
func uint64ToBase32(num uint64) []byte {
996✔
378
        // Return at least one group.
996✔
379
        if num == 0 {
1,038✔
380
                return []byte{0}
42✔
381
        }
42✔
382

383
        // To fit an uint64, we need at most is ceil(64 / 5) = 13 groups.
384
        arr := make([]byte, 13)
957✔
385
        i := 13
957✔
386
        for num > 0 {
3,639✔
387
                i--
2,682✔
388
                arr[i] = byte(num & uint64(31)) // 0b11111 in binary
2,682✔
389
                num >>= 5
2,682✔
390
        }
2,682✔
391

392
        // We only return non-zero leading groups.
393
        return arr[i:]
957✔
394
}
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