package sweep import ( "bytes" "encoding/binary" "errors" "fmt" "github.com/btcsuite/btcd/chaincfg/chainhash" "github.com/btcsuite/btcd/wire" "github.com/lightningnetwork/lnd/channeldb/kvdb" ) var ( // lastTxBucketKey is the key that points to a bucket containing a // single item storing the last published tx. // // maps: lastTxKey -> serialized_tx lastTxBucketKey = []byte("sweeper-last-tx") // lastTxKey is the fixed key under which the serialized tx is stored. lastTxKey = []byte("last-tx") // txHashesBucketKey is the key that points to a bucket containing the // hashes of all sweep txes that were published successfully. // // maps: txHash -> empty slice txHashesBucketKey = []byte("sweeper-tx-hashes") // utxnChainPrefix is the bucket prefix for nursery buckets. utxnChainPrefix = []byte("utxn") // utxnHeightIndexKey is the sub bucket where the nursery stores the // height index. utxnHeightIndexKey = []byte("height-index") // utxnFinalizedKndrTxnKey is a static key that can be used to locate // the nursery finalized kindergarten sweep txn. utxnFinalizedKndrTxnKey = []byte("finalized-kndr-txn") byteOrder = binary.BigEndian errNoTxHashesBucket = errors.New("tx hashes bucket does not exist") ) // SweeperStore stores published txes. type SweeperStore interface { // IsOurTx determines whether a tx is published by us, based on its // hash. IsOurTx(hash chainhash.Hash) (bool, error) // NotifyPublishTx signals that we are about to publish a tx. NotifyPublishTx(*wire.MsgTx) error // GetLastPublishedTx returns the last tx that we called NotifyPublishTx // for. GetLastPublishedTx() (*wire.MsgTx, error) // ListSweeps lists all the sweeps we have successfully published. ListSweeps() ([]chainhash.Hash, error) } type sweeperStore struct { db kvdb.Backend } // NewSweeperStore returns a new store instance. func NewSweeperStore(db kvdb.Backend, chainHash *chainhash.Hash) ( SweeperStore, error) { err := kvdb.Update(db, func(tx kvdb.RwTx) error { _, err := tx.CreateTopLevelBucket( lastTxBucketKey, ) if err != nil { return err } if tx.ReadWriteBucket(txHashesBucketKey) != nil { return nil } txHashesBucket, err := tx.CreateTopLevelBucket( txHashesBucketKey, ) if err != nil { return err } // Use non-existence of tx hashes bucket as a signal to migrate // nursery finalized txes. err = migrateTxHashes(tx, txHashesBucket, chainHash) return err }) if err != nil { return nil, err } return &sweeperStore{ db: db, }, nil } // migrateTxHashes migrates nursery finalized txes to the tx hashes bucket. This // is not implemented as a database migration, to keep the downgrade path open. func migrateTxHashes(tx kvdb.RwTx, txHashesBucket kvdb.RwBucket, chainHash *chainhash.Hash) error { log.Infof("Migrating UTXO nursery finalized TXIDs") // Compose chain bucket key. var b bytes.Buffer if _, err := b.Write(utxnChainPrefix); err != nil { return err } if _, err := b.Write(chainHash[:]); err != nil { return err } // Get chain bucket if exists. chainBucket := tx.ReadWriteBucket(b.Bytes()) if chainBucket == nil { return nil } // Retrieve the existing height index. hghtIndex := chainBucket.NestedReadWriteBucket(utxnHeightIndexKey) if hghtIndex == nil { return nil } // Retrieve all heights. err := hghtIndex.ForEach(func(k, v []byte) error { heightBucket := hghtIndex.NestedReadWriteBucket(k) if heightBucket == nil { return nil } // Get finalized tx for height. txBytes := heightBucket.Get(utxnFinalizedKndrTxnKey) if txBytes == nil { return nil } // Deserialize and skip tx if it cannot be deserialized. tx := &wire.MsgTx{} err := tx.Deserialize(bytes.NewReader(txBytes)) if err != nil { log.Warnf("Cannot deserialize utxn tx") return nil } // Calculate hash. hash := tx.TxHash() // Insert utxn tx hash in hashes bucket. log.Debugf("Inserting nursery tx %v in hash list "+ "(height=%v)", hash, byteOrder.Uint32(k)) return txHashesBucket.Put(hash[:], []byte{}) }) if err != nil { return err } return nil } // NotifyPublishTx signals that we are about to publish a tx. func (s *sweeperStore) NotifyPublishTx(sweepTx *wire.MsgTx) error { return kvdb.Update(s.db, func(tx kvdb.RwTx) error { lastTxBucket := tx.ReadWriteBucket(lastTxBucketKey) if lastTxBucket == nil { return errors.New("last tx bucket does not exist") } txHashesBucket := tx.ReadWriteBucket(txHashesBucketKey) if txHashesBucket == nil { return errNoTxHashesBucket } var b bytes.Buffer if err := sweepTx.Serialize(&b); err != nil { return err } if err := lastTxBucket.Put(lastTxKey, b.Bytes()); err != nil { return err } hash := sweepTx.TxHash() return txHashesBucket.Put(hash[:], []byte{}) }) } // GetLastPublishedTx returns the last tx that we called NotifyPublishTx // for. func (s *sweeperStore) GetLastPublishedTx() (*wire.MsgTx, error) { var sweepTx *wire.MsgTx err := kvdb.View(s.db, func(tx kvdb.ReadTx) error { lastTxBucket := tx.ReadBucket(lastTxBucketKey) if lastTxBucket == nil { return errors.New("last tx bucket does not exist") } sweepTxRaw := lastTxBucket.Get(lastTxKey) if sweepTxRaw == nil { return nil } sweepTx = &wire.MsgTx{} txReader := bytes.NewReader(sweepTxRaw) if err := sweepTx.Deserialize(txReader); err != nil { return fmt.Errorf("tx deserialize: %v", err) } return nil }) if err != nil { return nil, err } return sweepTx, nil } // IsOurTx determines whether a tx is published by us, based on its // hash. func (s *sweeperStore) IsOurTx(hash chainhash.Hash) (bool, error) { var ours bool err := kvdb.View(s.db, func(tx kvdb.ReadTx) error { txHashesBucket := tx.ReadBucket(txHashesBucketKey) if txHashesBucket == nil { return errNoTxHashesBucket } ours = txHashesBucket.Get(hash[:]) != nil return nil }) if err != nil { return false, err } return ours, nil } // ListSweeps lists all the sweep transactions we have in the sweeper store. func (s *sweeperStore) ListSweeps() ([]chainhash.Hash, error) { var sweepTxns []chainhash.Hash if err := kvdb.View(s.db, func(tx kvdb.ReadTx) error { txHashesBucket := tx.ReadBucket(txHashesBucketKey) if txHashesBucket == nil { return errNoTxHashesBucket } return txHashesBucket.ForEach(func(resKey, _ []byte) error { txid, err := chainhash.NewHash(resKey) if err != nil { return err } sweepTxns = append(sweepTxns, *txid) return nil }) }); err != nil { return nil, err } return sweepTxns, nil } // Compile-time constraint to ensure sweeperStore implements SweeperStore. var _ SweeperStore = (*sweeperStore)(nil)