|
| 1 | +package main |
| 2 | + |
| 3 | +import ( |
| 4 | + "bytes" |
| 5 | + "encoding/hex" |
| 6 | + "fmt" |
| 7 | + |
| 8 | + "github.com/btcsuite/btcd/btcutil" |
| 9 | + "github.com/btcsuite/btcd/chaincfg/chainhash" |
| 10 | + "github.com/btcsuite/btcd/txscript" |
| 11 | + "github.com/btcsuite/btcd/wire" |
| 12 | + "github.com/guggero/chantools/btc" |
| 13 | + "github.com/guggero/chantools/lnd" |
| 14 | + "github.com/lightninglabs/loop" |
| 15 | + "github.com/lightninglabs/loop/loopdb" |
| 16 | + "github.com/lightninglabs/loop/swap" |
| 17 | + "github.com/lightningnetwork/lnd/input" |
| 18 | + "github.com/lightningnetwork/lnd/keychain" |
| 19 | + "github.com/lightningnetwork/lnd/lnwallet/chainfee" |
| 20 | + "github.com/spf13/cobra" |
| 21 | +) |
| 22 | + |
| 23 | +type recoverLoopInCommand struct { |
| 24 | + TxID string |
| 25 | + Vout uint32 |
| 26 | + SwapHash string |
| 27 | + SweepAddr string |
| 28 | + FeeRate uint16 |
| 29 | + StartKeyIndex int |
| 30 | + NumTries int |
| 31 | + |
| 32 | + APIURL string |
| 33 | + Publish bool |
| 34 | + |
| 35 | + LoopDbPath string |
| 36 | + |
| 37 | + rootKey *rootKey |
| 38 | + cmd *cobra.Command |
| 39 | +} |
| 40 | + |
| 41 | +func newRecoverLoopInCommand() *cobra.Command { |
| 42 | + cc := &recoverLoopInCommand{} |
| 43 | + cc.cmd = &cobra.Command{ |
| 44 | + Use: "recoverloopin", |
| 45 | + Short: "Recover a loop in swap that the loop daemon " + |
| 46 | + "is not able to sweep", |
| 47 | + Example: `chantools recoverloopin \ |
| 48 | + --txid abcdef01234... \ |
| 49 | + --vout 0 \ |
| 50 | + --swap_hash abcdef01234... \ |
| 51 | + --loop_db_path /path/to/loop.db \ |
| 52 | + --sweep_addr bc1pxxxxxxx \ |
| 53 | + --feerate 10`, |
| 54 | + RunE: cc.Execute, |
| 55 | + } |
| 56 | + cc.cmd.Flags().StringVar( |
| 57 | + &cc.TxID, "txid", "", "transaction id of the on-chain "+ |
| 58 | + "transaction that created the HTLC", |
| 59 | + ) |
| 60 | + cc.cmd.Flags().Uint32Var( |
| 61 | + &cc.Vout, "vout", 0, "output index of the on-chain "+ |
| 62 | + "transaction that created the HTLC", |
| 63 | + ) |
| 64 | + cc.cmd.Flags().StringVar( |
| 65 | + &cc.SwapHash, "swap_hash", "", "swap hash of the loop in "+ |
| 66 | + "swap", |
| 67 | + ) |
| 68 | + cc.cmd.Flags().StringVar( |
| 69 | + &cc.LoopDbPath, "loop_db_path", "", "path to the loop "+ |
| 70 | + "database file", |
| 71 | + ) |
| 72 | + cc.cmd.Flags().StringVar( |
| 73 | + &cc.SweepAddr, "sweep_addr", "", "address to recover "+ |
| 74 | + "the funds to", |
| 75 | + ) |
| 76 | + cc.cmd.Flags().Uint16Var( |
| 77 | + &cc.FeeRate, "feerate", 0, "fee rate to "+ |
| 78 | + "use for the sweep transaction in sat/vByte", |
| 79 | + ) |
| 80 | + cc.cmd.Flags().IntVar( |
| 81 | + &cc.NumTries, "num_tries", 1000, "number of tries to "+ |
| 82 | + "try to find the correct key index", |
| 83 | + ) |
| 84 | + cc.cmd.Flags().IntVar( |
| 85 | + &cc.StartKeyIndex, "start_key_index", 0, "start key index "+ |
| 86 | + "to try to find the correct key index", |
| 87 | + ) |
| 88 | + cc.cmd.Flags().StringVar( |
| 89 | + &cc.APIURL, "apiurl", defaultAPIURL, "API URL to use (must "+ |
| 90 | + "be esplora compatible)", |
| 91 | + ) |
| 92 | + cc.cmd.Flags().BoolVar( |
| 93 | + &cc.Publish, "publish", false, "publish sweep TX to the chain "+ |
| 94 | + "API instead of just printing the TX", |
| 95 | + ) |
| 96 | + |
| 97 | + cc.rootKey = newRootKey(cc.cmd, "deriving starting key") |
| 98 | + |
| 99 | + return cc.cmd |
| 100 | +} |
| 101 | + |
| 102 | +func (c *recoverLoopInCommand) Execute(_ *cobra.Command, _ []string) error { |
| 103 | + extendedKey, err := c.rootKey.read() |
| 104 | + if err != nil { |
| 105 | + return fmt.Errorf("error reading root key: %w", err) |
| 106 | + } |
| 107 | + |
| 108 | + api := &btc.ExplorerAPI{BaseURL: c.APIURL} |
| 109 | + |
| 110 | + signer := &lnd.Signer{ |
| 111 | + ExtendedKey: extendedKey, |
| 112 | + ChainParams: chainParams, |
| 113 | + } |
| 114 | + |
| 115 | + // Try to fetch the swap from the database. |
| 116 | + store, err := loopdb.NewBoltSwapStore(c.LoopDbPath, chainParams) |
| 117 | + if err != nil { |
| 118 | + return err |
| 119 | + } |
| 120 | + defer store.Close() |
| 121 | + |
| 122 | + swaps, err := store.FetchLoopInSwaps() |
| 123 | + if err != nil { |
| 124 | + return err |
| 125 | + } |
| 126 | + |
| 127 | + var loopIn *loopdb.LoopIn |
| 128 | + for _, s := range swaps { |
| 129 | + if s.Hash.String() == c.SwapHash { |
| 130 | + loopIn = s |
| 131 | + break |
| 132 | + } |
| 133 | + } |
| 134 | + if loopIn == nil { |
| 135 | + return fmt.Errorf("swap not found") |
| 136 | + } |
| 137 | + |
| 138 | + fmt.Println("Loop expires at block height", loopIn.Contract.CltvExpiry) |
| 139 | + |
| 140 | + // Get the swaps htlc. |
| 141 | + htlc, err := loop.GetHtlc( |
| 142 | + loopIn.Hash, &loopIn.Contract.SwapContract, chainParams, |
| 143 | + ) |
| 144 | + if err != nil { |
| 145 | + return err |
| 146 | + } |
| 147 | + |
| 148 | + // Get the destination address. |
| 149 | + sweepAddr, err := btcutil.DecodeAddress(c.SweepAddr, chainParams) |
| 150 | + if err != nil { |
| 151 | + return err |
| 152 | + } |
| 153 | + |
| 154 | + // Calculate the sweep fee. |
| 155 | + estimator := &input.TxWeightEstimator{} |
| 156 | + err = htlc.AddTimeoutToEstimator(estimator) |
| 157 | + if err != nil { |
| 158 | + return err |
| 159 | + } |
| 160 | + |
| 161 | + switch sweepAddr.(type) { |
| 162 | + case *btcutil.AddressWitnessPubKeyHash: |
| 163 | + estimator.AddP2WKHOutput() |
| 164 | + |
| 165 | + case *btcutil.AddressTaproot: |
| 166 | + estimator.AddP2TROutput() |
| 167 | + |
| 168 | + default: |
| 169 | + return fmt.Errorf("unsupported address type") |
| 170 | + } |
| 171 | + |
| 172 | + feeRateKWeight := chainfee.SatPerKVByte(1000 * c.FeeRate).FeePerKWeight() |
| 173 | + fee := feeRateKWeight.FeeForWeight(int64(estimator.Weight())) |
| 174 | + |
| 175 | + txID, err := chainhash.NewHashFromStr(c.TxID) |
| 176 | + if err != nil { |
| 177 | + return err |
| 178 | + } |
| 179 | + |
| 180 | + // Get the htlc outpoint. |
| 181 | + htlcOutpoint := wire.OutPoint{ |
| 182 | + Hash: *txID, |
| 183 | + Index: c.Vout, |
| 184 | + } |
| 185 | + |
| 186 | + // Compose tx. |
| 187 | + sweepTx := wire.NewMsgTx(2) |
| 188 | + |
| 189 | + sweepTx.LockTime = uint32(loopIn.Contract.CltvExpiry) |
| 190 | + |
| 191 | + // Add HTLC input. |
| 192 | + sweepTx.AddTxIn(&wire.TxIn{ |
| 193 | + PreviousOutPoint: htlcOutpoint, |
| 194 | + Sequence: 0, |
| 195 | + }) |
| 196 | + |
| 197 | + // Add output for the destination address. |
| 198 | + sweepPkScript, err := txscript.PayToAddrScript(sweepAddr) |
| 199 | + if err != nil { |
| 200 | + return err |
| 201 | + } |
| 202 | + |
| 203 | + sweepTx.AddTxOut(&wire.TxOut{ |
| 204 | + PkScript: sweepPkScript, |
| 205 | + Value: int64(loopIn.Contract.AmountRequested) - int64(fee), |
| 206 | + }) |
| 207 | + |
| 208 | + // If the htlc is version 2, we need to brute force the key locator, as |
| 209 | + // it is not stored in the database. |
| 210 | + var rawTx []byte |
| 211 | + if htlc.Version == swap.HtlcV2 { |
| 212 | + fmt.Println("Brute forcing key index...") |
| 213 | + for i := c.StartKeyIndex; i < c.StartKeyIndex+c.NumTries; i++ { |
| 214 | + rawTx, err = getSignedTx( |
| 215 | + signer, loopIn, sweepTx, htlc, |
| 216 | + keychain.KeyFamily(swap.KeyFamily), uint32(i), |
| 217 | + ) |
| 218 | + if err == nil { |
| 219 | + break |
| 220 | + } |
| 221 | + } |
| 222 | + if rawTx == nil { |
| 223 | + return fmt.Errorf("failed to brute force key index, " + |
| 224 | + "please try again with a higher start key index") |
| 225 | + } |
| 226 | + } else { |
| 227 | + rawTx, err = getSignedTx( |
| 228 | + signer, loopIn, sweepTx, htlc, |
| 229 | + loopIn.Contract.HtlcKeys.ClientScriptKeyLocator.Family, |
| 230 | + loopIn.Contract.HtlcKeys.ClientScriptKeyLocator.Index, |
| 231 | + ) |
| 232 | + if err != nil { |
| 233 | + return err |
| 234 | + } |
| 235 | + } |
| 236 | + |
| 237 | + // Publish TX. |
| 238 | + if c.Publish { |
| 239 | + response, err := api.PublishTx( |
| 240 | + hex.EncodeToString(rawTx), |
| 241 | + ) |
| 242 | + if err != nil { |
| 243 | + return err |
| 244 | + } |
| 245 | + log.Infof("Published TX %s, response: %s", |
| 246 | + sweepTx.TxHash().String(), response) |
| 247 | + } else { |
| 248 | + fmt.Printf("Success, we successfully created the sweep transaction. "+ |
| 249 | + "Please publish this using any bitcoin node:\n\n%x\n\n", |
| 250 | + rawTx) |
| 251 | + } |
| 252 | + |
| 253 | + return nil |
| 254 | +} |
| 255 | + |
| 256 | +func getSignedTx(signer *lnd.Signer, loopIn *loopdb.LoopIn, sweepTx *wire.MsgTx, |
| 257 | + htlc *swap.Htlc, keyFamily keychain.KeyFamily, |
| 258 | + keyIndex uint32) ([]byte, error) { |
| 259 | + |
| 260 | + // Create the sign descriptor. |
| 261 | + prevoutFetcher := txscript.NewCannedPrevOutputFetcher( |
| 262 | + htlc.PkScript, int64(loopIn.Contract.AmountRequested), |
| 263 | + ) |
| 264 | + |
| 265 | + signDesc := &input.SignDescriptor{ |
| 266 | + KeyDesc: keychain.KeyDescriptor{ |
| 267 | + KeyLocator: keychain.KeyLocator{ |
| 268 | + Family: keyFamily, |
| 269 | + Index: keyIndex, |
| 270 | + }, |
| 271 | + }, |
| 272 | + WitnessScript: htlc.TimeoutScript(), |
| 273 | + HashType: htlc.SigHash(), |
| 274 | + InputIndex: 0, |
| 275 | + PrevOutputFetcher: prevoutFetcher, |
| 276 | + Output: &wire.TxOut{ |
| 277 | + PkScript: htlc.PkScript, |
| 278 | + Value: int64(loopIn.Contract.AmountRequested), |
| 279 | + }, |
| 280 | + } |
| 281 | + switch htlc.Version { |
| 282 | + case swap.HtlcV2: |
| 283 | + signDesc.SignMethod = input.WitnessV0SignMethod |
| 284 | + |
| 285 | + case swap.HtlcV3: |
| 286 | + signDesc.SignMethod = input.TaprootScriptSpendSignMethod |
| 287 | + } |
| 288 | + |
| 289 | + sig, err := signer.SignOutputRaw(sweepTx, signDesc) |
| 290 | + if err != nil { |
| 291 | + return nil, err |
| 292 | + } |
| 293 | + |
| 294 | + witness, err := htlc.GenTimeoutWitness(sig.Serialize()) |
| 295 | + if err != nil { |
| 296 | + return nil, err |
| 297 | + } |
| 298 | + |
| 299 | + sweepTx.TxIn[0].Witness = witness |
| 300 | + |
| 301 | + rawTx, err := encodeTx(sweepTx) |
| 302 | + if err != nil { |
| 303 | + return nil, err |
| 304 | + } |
| 305 | + |
| 306 | + sighashes := txscript.NewTxSigHashes(sweepTx, prevoutFetcher) |
| 307 | + |
| 308 | + // Verify the signature. This will throw an error if the signature is |
| 309 | + // invalid and allows us to bruteforce the key index. |
| 310 | + vm, err := txscript.NewEngine( |
| 311 | + htlc.PkScript, sweepTx, 0, txscript.StandardVerifyFlags, nil, |
| 312 | + sighashes, int64(loopIn.Contract.AmountRequested), prevoutFetcher, |
| 313 | + ) |
| 314 | + if err != nil { |
| 315 | + return nil, err |
| 316 | + } |
| 317 | + |
| 318 | + err = vm.Execute() |
| 319 | + if err != nil { |
| 320 | + return nil, err |
| 321 | + } |
| 322 | + |
| 323 | + return rawTx, nil |
| 324 | +} |
| 325 | + |
| 326 | +// encodeTx encodes a tx to raw bytes. |
| 327 | +func encodeTx(tx *wire.MsgTx) ([]byte, error) { |
| 328 | + var buffer bytes.Buffer |
| 329 | + err := tx.BtcEncode(&buffer, 0, wire.WitnessEncoding) |
| 330 | + if err != nil { |
| 331 | + return nil, err |
| 332 | + } |
| 333 | + rawTx := buffer.Bytes() |
| 334 | + |
| 335 | + return rawTx, nil |
| 336 | +} |
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