12312390362

Committed 13 Dec 2024 08:44AM UTC coverage: 57.458% (+8.5%) from 48.92%

Build # 12312390362

Build Type

Pull #9343

github

Committed by

ellemouton

Commit Message

fn: rework the ContextGuard and add tests

In this commit, the ContextGuard struct is re-worked such that the
context that its new main WithCtx method provides is cancelled in sync
with a parent context being cancelled or with it's quit channel being
cancelled. Tests are added to assert the behaviour. In order for the
close of the quit channel to be consistent with the cancelling of the
derived context, the quit channel _must_ be contained internal to the
ContextGuard so that callers are only able to close the channel via the
exposed Quit method which will then take care to first cancel any
derived context that depend on the quit channel before returning.

Pull Request Pull Request #9343: fn: expand the ContextGuard and add tests

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68.47

/sweep/txgenerator.go

package sweep

import (
        "errors"
        "fmt"
        "sort"
        "strings"

        "github.com/btcsuite/btcd/blockchain"
        "github.com/btcsuite/btcd/btcutil"
        "github.com/btcsuite/btcd/txscript"
        "github.com/btcsuite/btcd/wire"
        "github.com/lightningnetwork/lnd/input"
        "github.com/lightningnetwork/lnd/lnwallet"
        "github.com/lightningnetwork/lnd/lnwallet/chainfee"
)

var (
        // DefaultMaxInputsPerTx specifies the default maximum number of inputs
        // allowed in a single sweep tx. If more need to be swept, multiple txes
        // are created and published.
        DefaultMaxInputsPerTx = uint32(100)

        // ErrLocktimeConflict is returned when inputs with different
        // transaction nLockTime values are included in the same transaction.
        //
        // NOTE: due the SINGLE|ANYONECANPAY sighash flag, which is used in the
        // second level success/timeout txns, only the txns sharing the same
        // nLockTime can exist in the same tx.
        ErrLocktimeConflict = errors.New("incompatible locktime")
)

// createSweepTx builds a signed tx spending the inputs to the given outputs,
// sending any leftover change to the change script.
func createSweepTx(inputs []input.Input, outputs []*wire.TxOut,
        changePkScript []byte, currentBlockHeight uint32,
        feeRate, maxFeeRate chainfee.SatPerKWeight,
        signer input.Signer) (*wire.MsgTx, btcutil.Amount, error) {

        inputs, estimator, err := getWeightEstimate(
                inputs, outputs, feeRate, maxFeeRate, [][]byte{changePkScript},
        )
        if err != nil {
                return nil, 0, err
        }

        txFee := estimator.feeWithParent()

        var (
                // Create the sweep transaction that we will be building. We
                // use version 2 as it is required for CSV.
                sweepTx = wire.NewMsgTx(2)

                // Track whether any of the inputs require a certain locktime.
                locktime = int32(-1)

                // We keep track of total input amount, and required output
                // amount to use for calculating the change amount below.
                totalInput     btcutil.Amount
                requiredOutput btcutil.Amount

                // We'll add the inputs as we go so we know the final ordering
                // of inputs to sign.
                idxs []input.Input
        )

        // We start by adding all inputs that commit to an output. We do this
        // since the input and output index must stay the same for the
        // signatures to be valid.
        for _, o := range inputs {
                if o.RequiredTxOut() == nil {
                        continue
                }

                idxs = append(idxs, o)
                sweepTx.AddTxIn(&wire.TxIn{
                        PreviousOutPoint: o.OutPoint(),
                        Sequence:         o.BlocksToMaturity(),
                })
                sweepTx.AddTxOut(o.RequiredTxOut())

                if lt, ok := o.RequiredLockTime(); ok {
                        // If another input commits to a different locktime,
                        // they cannot be combined in the same transaction.
                        if locktime != -1 && locktime != int32(lt) {
                                return nil, 0, ErrLocktimeConflict
                        }

                        locktime = int32(lt)
                }

                totalInput += btcutil.Amount(o.SignDesc().Output.Value)
                requiredOutput += btcutil.Amount(o.RequiredTxOut().Value)
        }

        // Sum up the value contained in the remaining inputs, and add them to
        // the sweep transaction.
        for _, o := range inputs {
                if o.RequiredTxOut() != nil {
                        continue
                }

                idxs = append(idxs, o)
                sweepTx.AddTxIn(&wire.TxIn{
                        PreviousOutPoint: o.OutPoint(),
                        Sequence:         o.BlocksToMaturity(),
                })

                if lt, ok := o.RequiredLockTime(); ok {
                        if locktime != -1 && locktime != int32(lt) {
                                return nil, 0, ErrLocktimeConflict
                        }

                        locktime = int32(lt)
                }

                totalInput += btcutil.Amount(o.SignDesc().Output.Value)
        }

        // Add the outputs given, if any.
        for _, o := range outputs {
                sweepTx.AddTxOut(o)
                requiredOutput += btcutil.Amount(o.Value)
        }

        if requiredOutput+txFee > totalInput {
                return nil, 0, fmt.Errorf("insufficient input to create sweep "+
                        "tx: input_sum=%v, output_sum=%v", totalInput,
                        requiredOutput+txFee)
        }

        // The value remaining after the required output and fees, go to
        // change. Not that this fee is what we would have to pay in case the
        // sweep tx has a change output.
        changeAmt := totalInput - requiredOutput - txFee

        // We'll calculate the dust limit for the given changePkScript since it
        // is variable.
        changeLimit := lnwallet.DustLimitForSize(len(changePkScript))

        // The txn will sweep the amount after fees to the pkscript generated
        // above.
        if changeAmt >= changeLimit {
                sweepTx.AddTxOut(&wire.TxOut{
                        PkScript: changePkScript,
                        Value:    int64(changeAmt),
                })
        } else {
                log.Infof("Change amt %v below dustlimit %v, not adding "+
                        "change output", changeAmt, changeLimit)

                // The dust amount is added to the fee as the miner will
                // collect it.
                txFee += changeAmt
        }

        // We'll default to using the current block height as locktime, if none
        // of the inputs commits to a different locktime.
        sweepTx.LockTime = currentBlockHeight
        if locktime != -1 {
                sweepTx.LockTime = uint32(locktime)
        }

        // Before signing the transaction, check to ensure that it meets some
        // basic validity requirements.
        //
        // TODO(conner): add more control to sanity checks, allowing us to
        // delay spending "problem" outputs, e.g. possibly batching with other
        // classes if fees are too low.
        btx := btcutil.NewTx(sweepTx)
        if err := blockchain.CheckTransactionSanity(btx); err != nil {
                return nil, 0, err
        }

        prevInputFetcher, err := input.MultiPrevOutFetcher(inputs)
        if err != nil {
                return nil, 0, fmt.Errorf("error creating prev input fetcher "+
                        "for hash cache: %v", err)
        }
        hashCache := txscript.NewTxSigHashes(sweepTx, prevInputFetcher)

        // With all the inputs in place, use each output's unique input script
        // function to generate the final witness required for spending.
        addInputScript := func(idx int, tso input.Input) error {
                inputScript, err := tso.CraftInputScript(
                        signer, sweepTx, hashCache, prevInputFetcher, idx,
                )
                if err != nil {
                        return err
                }

                sweepTx.TxIn[idx].Witness = inputScript.Witness

                if len(inputScript.SigScript) != 0 {
                        sweepTx.TxIn[idx].SignatureScript =
                                inputScript.SigScript
                }

                return nil
        }

        for idx, inp := range idxs {
                if err := addInputScript(idx, inp); err != nil {
                        return nil, 0, err
                }
        }

        log.Debugf("Creating sweep transaction %v for %v inputs (%s) "+
                "using %v, tx_weight=%v, tx_fee=%v, parents_count=%v, "+
                "parents_fee=%v, parents_weight=%v, current_height=%v",
                sweepTx.TxHash(), len(inputs),
                inputTypeSummary(inputs), feeRate,
                estimator.weight(), txFee,
                len(estimator.parents), estimator.parentsFee,
                estimator.parentsWeight, currentBlockHeight)

        return sweepTx, txFee, nil
}

// getWeightEstimate returns a weight estimate for the given inputs.
// Additionally, it returns counts for the number of csv and cltv inputs.
func getWeightEstimate(inputs []input.Input, outputs []*wire.TxOut,
        feeRate, maxFeeRate chainfee.SatPerKWeight,
        outputPkScripts [][]byte) ([]input.Input, *weightEstimator, error) {

        // We initialize a weight estimator so we can accurately asses the
        // amount of fees we need to pay for this sweep transaction.
        //
        // TODO(roasbeef): can be more intelligent about buffering outputs to
        // be more efficient on-chain.
        weightEstimate := newWeightEstimator(feeRate, maxFeeRate)

        // Our sweep transaction will always pay to the given set of outputs.
        for _, o := range outputs {
                weightEstimate.addOutput(o)
        }

        // If there is any leftover change after paying to the given outputs
        // and required outputs, it will go to a single segwit p2wkh or p2tr
        // address. This will be our change address, so ensure it contributes
        // to our weight estimate. Note that if we have other outputs, we might
        // end up creating a sweep tx without a change output. It is okay to
        // add the change output to the weight estimate regardless, since the
        // estimated fee will just be subtracted from this already dust output,
        // and trimmed.
        for _, outputPkScript := range outputPkScripts {
                switch {
                case txscript.IsPayToTaproot(outputPkScript):
                        weightEstimate.addP2TROutput()

                case txscript.IsPayToWitnessScriptHash(outputPkScript):
                        weightEstimate.addP2WSHOutput()

                case txscript.IsPayToWitnessPubKeyHash(outputPkScript):
                        weightEstimate.addP2WKHOutput()

                case txscript.IsPayToPubKeyHash(outputPkScript):
                        weightEstimate.estimator.AddP2PKHOutput()

                case txscript.IsPayToScriptHash(outputPkScript):
                        weightEstimate.estimator.AddP2SHOutput()

                default:
                        // Unknown script type.
                        return nil, nil, fmt.Errorf("unknown script "+
                                "type: %x", outputPkScript)
                }
        }

        // For each output, use its witness type to determine the estimate
        // weight of its witness, and add it to the proper set of spendable
        // outputs.
        var sweepInputs []input.Input
        for i := range inputs {
                inp := inputs[i]

                err := weightEstimate.add(inp)
                if err != nil {
                        // TODO(yy): check if this is even possible? If so, we
                        // should return the error here instead of filtering!
                        log.Errorf("Failed to get weight estimate for "+
                                "input=%v, witnessType=%v: %v ", inp.OutPoint(),
                                inp.WitnessType(), err)

                        // Skip inputs for which no weight estimate can be
                        // given.
                        continue
                }

                // If this input comes with a committed output, add that as
                // well.
                if inp.RequiredTxOut() != nil {
                        weightEstimate.addOutput(inp.RequiredTxOut())
                }

                sweepInputs = append(sweepInputs, inp)
        }

        return sweepInputs, weightEstimate, nil
}

// inputSummary returns a string containing a human readable summary about the
// witness types of a list of inputs.
func inputTypeSummary(inputs []input.Input) string {
        // Sort inputs by witness type.
        sortedInputs := make([]input.Input, len(inputs))
        copy(sortedInputs, inputs)
        sort.Slice(sortedInputs, func(i, j int) bool {
                return sortedInputs[i].WitnessType().String() <
                        sortedInputs[j].WitnessType().String()
        })

        var parts []string
        for _, i := range sortedInputs {
                part := fmt.Sprintf("%v (%v)", i.OutPoint(), i.WitnessType())
                parts = append(parts, part)
        }
        return strings.Join(parts, ", ")
}

1	package sweep
2
3	import (
4	"errors"
5	"fmt"
6	"sort"
7	"strings"
8
9	"github.com/btcsuite/btcd/blockchain"
10	"github.com/btcsuite/btcd/btcutil"
11	"github.com/btcsuite/btcd/txscript"
12	"github.com/btcsuite/btcd/wire"
13	"github.com/lightningnetwork/lnd/input"
14	"github.com/lightningnetwork/lnd/lnwallet"
15	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
16	)
17
18	var (
19	// DefaultMaxInputsPerTx specifies the default maximum number of inputs
20	// allowed in a single sweep tx. If more need to be swept, multiple txes
21	// are created and published.
22	DefaultMaxInputsPerTx = uint32(100)
23
24	// ErrLocktimeConflict is returned when inputs with different
25	// transaction nLockTime values are included in the same transaction.
26	//
27	// NOTE: due the SINGLE\|ANYONECANPAY sighash flag, which is used in the
28	// second level success/timeout txns, only the txns sharing the same
29	// nLockTime can exist in the same tx.
30	ErrLocktimeConflict = errors.New("incompatible locktime")
31	)
32
33	// createSweepTx builds a signed tx spending the inputs to the given outputs,
34	// sending any leftover change to the change script.
35	func createSweepTx(inputs []input.Input, outputs []*wire.TxOut,
36	changePkScript []byte, currentBlockHeight uint32,
37	feeRate, maxFeeRate chainfee.SatPerKWeight,
38	signer input.Signer) (*wire.MsgTx, btcutil.Amount, error) {	2✔
39		2✔
40	inputs, estimator, err := getWeightEstimate(	2✔
41	inputs, outputs, feeRate, maxFeeRate, [][]byte{changePkScript},	2✔
42	)	2✔
43	if err != nil {	2✔
44	return nil, 0, err	×
45	}	×
46
47	txFee := estimator.feeWithParent()	2✔
48		2✔
49	var (	2✔
50	// Create the sweep transaction that we will be building. We	2✔
51	// use version 2 as it is required for CSV.	2✔
52	sweepTx = wire.NewMsgTx(2)	2✔
53		2✔
54	// Track whether any of the inputs require a certain locktime.	2✔
55	locktime = int32(-1)	2✔
56		2✔
57	// We keep track of total input amount, and required output	2✔
58	// amount to use for calculating the change amount below.	2✔
59	totalInput btcutil.Amount	2✔
60	requiredOutput btcutil.Amount	2✔
61		2✔
62	// We'll add the inputs as we go so we know the final ordering	2✔
63	// of inputs to sign.	2✔
64	idxs []input.Input	2✔
65	)	2✔
66		2✔
67	// We start by adding all inputs that commit to an output. We do this	2✔
68	// since the input and output index must stay the same for the	2✔
69	// signatures to be valid.	2✔
70	for _, o := range inputs {	5✔
71	if o.RequiredTxOut() == nil {	6✔
72	continue	3✔
73	}
74
75	idxs = append(idxs, o)	×
76	sweepTx.AddTxIn(&wire.TxIn{	×
77	PreviousOutPoint: o.OutPoint(),	×
78	Sequence: o.BlocksToMaturity(),	×
79	})	×
80	sweepTx.AddTxOut(o.RequiredTxOut())	×
81		×
82	if lt, ok := o.RequiredLockTime(); ok {	×
83	// If another input commits to a different locktime,	×
84	// they cannot be combined in the same transaction.	×
85	if locktime != -1 && locktime != int32(lt) {	×
86	return nil, 0, ErrLocktimeConflict	×
87	}	×
88
89	locktime = int32(lt)	×
90	}
91
92	totalInput += btcutil.Amount(o.SignDesc().Output.Value)	×
93	requiredOutput += btcutil.Amount(o.RequiredTxOut().Value)	×
94	}
95
96	// Sum up the value contained in the remaining inputs, and add them to
97	// the sweep transaction.
98	for _, o := range inputs {	5✔
99	if o.RequiredTxOut() != nil {	3✔
100	continue	×
101	}
102
103	idxs = append(idxs, o)	3✔
104	sweepTx.AddTxIn(&wire.TxIn{	3✔
105	PreviousOutPoint: o.OutPoint(),	3✔
106	Sequence: o.BlocksToMaturity(),	3✔
107	})	3✔
108		3✔
109	if lt, ok := o.RequiredLockTime(); ok {	3✔
110	if locktime != -1 && locktime != int32(lt) {	×
111	return nil, 0, ErrLocktimeConflict	×
112	}	×
113
114	locktime = int32(lt)	×
115	}
116
117	totalInput += btcutil.Amount(o.SignDesc().Output.Value)	3✔
118	}
119
120	// Add the outputs given, if any.
121	for _, o := range outputs {	2✔
122	sweepTx.AddTxOut(o)	×
123	requiredOutput += btcutil.Amount(o.Value)	×
124	}	×
125
126	if requiredOutput+txFee > totalInput {	2✔
127	return nil, 0, fmt.Errorf("insufficient input to create sweep "+	×
128	"tx: input_sum=%v, output_sum=%v", totalInput,	×
129	requiredOutput+txFee)	×
130	}	×
131
132	// The value remaining after the required output and fees, go to
133	// change. Not that this fee is what we would have to pay in case the
134	// sweep tx has a change output.
135	changeAmt := totalInput - requiredOutput - txFee	2✔
136		2✔
137	// We'll calculate the dust limit for the given changePkScript since it	2✔
138	// is variable.	2✔
139	changeLimit := lnwallet.DustLimitForSize(len(changePkScript))	2✔
140		2✔
141	// The txn will sweep the amount after fees to the pkscript generated	2✔
142	// above.	2✔
143	if changeAmt >= changeLimit {	4✔
144	sweepTx.AddTxOut(&wire.TxOut{	2✔
145	PkScript: changePkScript,	2✔
146	Value: int64(changeAmt),	2✔
147	})	2✔
148	} else {	2✔
149	log.Infof("Change amt %v below dustlimit %v, not adding "+	×
150	"change output", changeAmt, changeLimit)	×
151		×
152	// The dust amount is added to the fee as the miner will	×
153	// collect it.	×
154	txFee += changeAmt	×
155	}	×
156
157	// We'll default to using the current block height as locktime, if none
158	// of the inputs commits to a different locktime.
159	sweepTx.LockTime = currentBlockHeight	2✔
160	if locktime != -1 {	2✔
161	sweepTx.LockTime = uint32(locktime)	×
162	}	×
163
164	// Before signing the transaction, check to ensure that it meets some
165	// basic validity requirements.
166	//
167	// TODO(conner): add more control to sanity checks, allowing us to
168	// delay spending "problem" outputs, e.g. possibly batching with other
169	// classes if fees are too low.
170	btx := btcutil.NewTx(sweepTx)	2✔
171	if err := blockchain.CheckTransactionSanity(btx); err != nil {	2✔
172	return nil, 0, err	×
173	}	×
174
175	prevInputFetcher, err := input.MultiPrevOutFetcher(inputs)	2✔
176	if err != nil {	2✔
177	return nil, 0, fmt.Errorf("error creating prev input fetcher "+	×
178	"for hash cache: %v", err)	×
179	}	×
180	hashCache := txscript.NewTxSigHashes(sweepTx, prevInputFetcher)	2✔
181		2✔
182	// With all the inputs in place, use each output's unique input script	2✔
183	// function to generate the final witness required for spending.	2✔
184	addInputScript := func(idx int, tso input.Input) error {	5✔
185	inputScript, err := tso.CraftInputScript(	3✔
186	signer, sweepTx, hashCache, prevInputFetcher, idx,	3✔
187	)	3✔
188	if err != nil {	3✔
189	return err	×
190	}	×
191
192	sweepTx.TxIn[idx].Witness = inputScript.Witness	3✔
193		3✔
194	if len(inputScript.SigScript) != 0 {	3✔
195	sweepTx.TxIn[idx].SignatureScript =	×
196	inputScript.SigScript	×
197	}	×
198
199	return nil	3✔
200	}
201
202	for idx, inp := range idxs {	5✔
203	if err := addInputScript(idx, inp); err != nil {	3✔
204	return nil, 0, err	×
205	}	×
206	}
207
208	log.Debugf("Creating sweep transaction %v for %v inputs (%s) "+	2✔
209	"using %v, tx_weight=%v, tx_fee=%v, parents_count=%v, "+	2✔
210	"parents_fee=%v, parents_weight=%v, current_height=%v",	2✔
211	sweepTx.TxHash(), len(inputs),	2✔
212	inputTypeSummary(inputs), feeRate,	2✔
213	estimator.weight(), txFee,	2✔
214	len(estimator.parents), estimator.parentsFee,	2✔
215	estimator.parentsWeight, currentBlockHeight)	2✔
216		2✔
217	return sweepTx, txFee, nil	2✔
218	}
219
220	// getWeightEstimate returns a weight estimate for the given inputs.
221	// Additionally, it returns counts for the number of csv and cltv inputs.
222	func getWeightEstimate(inputs []input.Input, outputs []*wire.TxOut,
223	feeRate, maxFeeRate chainfee.SatPerKWeight,
224	outputPkScripts [][]byte) ([]input.Input, *weightEstimator, error) {	42✔
225		42✔
226	// We initialize a weight estimator so we can accurately asses the	42✔
227	// amount of fees we need to pay for this sweep transaction.	42✔
228	//	42✔
229	// TODO(roasbeef): can be more intelligent about buffering outputs to	42✔
230	// be more efficient on-chain.	42✔
231	weightEstimate := newWeightEstimator(feeRate, maxFeeRate)	42✔
232		42✔
233	// Our sweep transaction will always pay to the given set of outputs.	42✔
234	for _, o := range outputs {	42✔
235	weightEstimate.addOutput(o)	×
236	}	×
237
238	// If there is any leftover change after paying to the given outputs
239	// and required outputs, it will go to a single segwit p2wkh or p2tr
240	// address. This will be our change address, so ensure it contributes
241	// to our weight estimate. Note that if we have other outputs, we might
242	// end up creating a sweep tx without a change output. It is okay to
243	// add the change output to the weight estimate regardless, since the
244	// estimated fee will just be subtracted from this already dust output,
245	// and trimmed.
246	for _, outputPkScript := range outputPkScripts {	84✔
247	switch {	42✔
248	case txscript.IsPayToTaproot(outputPkScript):	32✔
249	weightEstimate.addP2TROutput()	32✔
250
251	case txscript.IsPayToWitnessScriptHash(outputPkScript):	1✔
252	weightEstimate.addP2WSHOutput()	1✔
253
254	case txscript.IsPayToWitnessPubKeyHash(outputPkScript):	4✔
255	weightEstimate.addP2WKHOutput()	4✔
256
257	case txscript.IsPayToPubKeyHash(outputPkScript):	1✔
258	weightEstimate.estimator.AddP2PKHOutput()	1✔
259
260	case txscript.IsPayToScriptHash(outputPkScript):	1✔
261	weightEstimate.estimator.AddP2SHOutput()	1✔
262
263	default:	3✔
264	// Unknown script type.	3✔
265	return nil, nil, fmt.Errorf("unknown script "+	3✔
266	"type: %x", outputPkScript)	3✔
267	}
268	}
269
270	// For each output, use its witness type to determine the estimate
271	// weight of its witness, and add it to the proper set of spendable
272	// outputs.
273	var sweepInputs []input.Input	39✔
274	for i := range inputs {	97✔
275	inp := inputs[i]	58✔
276		58✔
277	err := weightEstimate.add(inp)	58✔
278	if err != nil {	58✔
279	// TODO(yy): check if this is even possible? If so, we	×
280	// should return the error here instead of filtering!	×
281	log.Errorf("Failed to get weight estimate for "+	×
282	"input=%v, witnessType=%v: %v ", inp.OutPoint(),	×
283	inp.WitnessType(), err)	×
284		×
285	// Skip inputs for which no weight estimate can be	×
286	// given.	×
287	continue	×
288	}
289
290	// If this input comes with a committed output, add that as
291	// well.
292	if inp.RequiredTxOut() != nil {	58✔
293	weightEstimate.addOutput(inp.RequiredTxOut())	×
294	}	×
295
296	sweepInputs = append(sweepInputs, inp)	58✔
297	}
298
299	return sweepInputs, weightEstimate, nil	39✔
300	}
301
302	// inputSummary returns a string containing a human readable summary about the
303	// witness types of a list of inputs.
304	func inputTypeSummary(inputs []input.Input) string {	55✔
305	// Sort inputs by witness type.	55✔
306	sortedInputs := make([]input.Input, len(inputs))	55✔
307	copy(sortedInputs, inputs)	55✔
308	sort.Slice(sortedInputs, func(i, j int) bool {	59✔
309	return sortedInputs[i].WitnessType().String() <	4✔
310	sortedInputs[j].WitnessType().String()	4✔
311	})	4✔
312
313	var parts []string	55✔
314	for _, i := range sortedInputs {	112✔
315	part := fmt.Sprintf("%v (%v)", i.OutPoint(), i.WitnessType())	57✔
316	parts = append(parts, part)	57✔
317	}	57✔
318	return strings.Join(parts, ", ")	55✔
319	}

lightningnetwork / lnd / 12312390362

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