package btcwallet import ( "bytes" "encoding/hex" "fmt" "math" "sync" "time" "github.com/btcsuite/btcd/chaincfg" "github.com/btcsuite/btcd/chaincfg/chainhash" "github.com/btcsuite/btcd/txscript" "github.com/btcsuite/btcd/wire" "github.com/btcsuite/btcutil" "github.com/btcsuite/btcwallet/chain" "github.com/btcsuite/btcwallet/waddrmgr" base "github.com/btcsuite/btcwallet/wallet" "github.com/btcsuite/btcwallet/wallet/txauthor" "github.com/btcsuite/btcwallet/wallet/txrules" "github.com/btcsuite/btcwallet/walletdb" "github.com/btcsuite/btcwallet/wtxmgr" "github.com/lightningnetwork/lnd/keychain" "github.com/lightningnetwork/lnd/lnwallet" "github.com/lightningnetwork/lnd/lnwallet/chainfee" ) const ( defaultAccount = uint32(waddrmgr.DefaultAccountNum) // UnconfirmedHeight is the special case end height that is used to // obtain unconfirmed transactions from ListTransactionDetails. UnconfirmedHeight int32 = -1 ) var ( // waddrmgrNamespaceKey is the namespace key that the waddrmgr state is // stored within the top-level waleltdb buckets of btcwallet. waddrmgrNamespaceKey = []byte("waddrmgr") // lightningAddrSchema is the scope addr schema for all keys that we // derive. We'll treat them all as p2wkh addresses, as atm we must // specify a particular type. lightningAddrSchema = waddrmgr.ScopeAddrSchema{ ExternalAddrType: waddrmgr.WitnessPubKey, InternalAddrType: waddrmgr.WitnessPubKey, } ) // BtcWallet is an implementation of the lnwallet.WalletController interface // backed by an active instance of btcwallet. At the time of the writing of // this documentation, this implementation requires a full btcd node to // operate. type BtcWallet struct { // wallet is an active instance of btcwallet. wallet *base.Wallet chain chain.Interface db walletdb.DB cfg *Config netParams *chaincfg.Params chainKeyScope waddrmgr.KeyScope } // A compile time check to ensure that BtcWallet implements the // WalletController and BlockChainIO interfaces. var _ lnwallet.WalletController = (*BtcWallet)(nil) var _ lnwallet.BlockChainIO = (*BtcWallet)(nil) // New returns a new fully initialized instance of BtcWallet given a valid // configuration struct. func New(cfg Config) (*BtcWallet, error) { // Ensure the wallet exists or create it when the create flag is set. netDir := NetworkDir(cfg.DataDir, cfg.NetParams) // Create the key scope for the coin type being managed by this wallet. chainKeyScope := waddrmgr.KeyScope{ Purpose: keychain.BIP0043Purpose, Coin: cfg.CoinType, } // Maybe the wallet has already been opened and unlocked by the // WalletUnlocker. So if we get a non-nil value from the config, // we assume everything is in order. var wallet = cfg.Wallet if wallet == nil { // No ready wallet was passed, so try to open an existing one. var pubPass []byte if cfg.PublicPass == nil { pubPass = defaultPubPassphrase } else { pubPass = cfg.PublicPass } loader := base.NewLoader( cfg.NetParams, netDir, cfg.NoFreelistSync, cfg.RecoveryWindow, ) walletExists, err := loader.WalletExists() if err != nil { return nil, err } if !walletExists { // Wallet has never been created, perform initial // set up. wallet, err = loader.CreateNewWallet( pubPass, cfg.PrivatePass, cfg.HdSeed, cfg.Birthday, ) if err != nil { return nil, err } } else { // Wallet has been created and been initialized at // this point, open it along with all the required DB // namespaces, and the DB itself. wallet, err = loader.OpenExistingWallet(pubPass, false) if err != nil { return nil, err } } } return &BtcWallet{ cfg: &cfg, wallet: wallet, db: wallet.Database(), chain: cfg.ChainSource, netParams: cfg.NetParams, chainKeyScope: chainKeyScope, }, nil } // BackEnd returns the underlying ChainService's name as a string. // // This is a part of the WalletController interface. func (b *BtcWallet) BackEnd() string { if b.chain != nil { return b.chain.BackEnd() } return "" } // InternalWallet returns a pointer to the internal base wallet which is the // core of btcwallet. func (b *BtcWallet) InternalWallet() *base.Wallet { return b.wallet } // Start initializes the underlying rpc connection, the wallet itself, and // begins syncing to the current available blockchain state. // // This is a part of the WalletController interface. func (b *BtcWallet) Start() error { // We'll start by unlocking the wallet and ensuring that the KeyScope: // (1017, 1) exists within the internal waddrmgr. We'll need this in // order to properly generate the keys required for signing various // contracts. if err := b.wallet.Unlock(b.cfg.PrivatePass, nil); err != nil { return err } _, err := b.wallet.Manager.FetchScopedKeyManager(b.chainKeyScope) if err != nil { // If the scope hasn't yet been created (it wouldn't been // loaded by default if it was), then we'll manually create the // scope for the first time ourselves. err := walletdb.Update(b.db, func(tx walletdb.ReadWriteTx) error { addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey) _, err := b.wallet.Manager.NewScopedKeyManager( addrmgrNs, b.chainKeyScope, lightningAddrSchema, ) return err }) if err != nil { return err } } // Establish an RPC connection in addition to starting the goroutines // in the underlying wallet. if err := b.chain.Start(); err != nil { return err } // Start the underlying btcwallet core. b.wallet.Start() // Pass the rpc client into the wallet so it can sync up to the // current main chain. b.wallet.SynchronizeRPC(b.chain) return nil } // Stop signals the wallet for shutdown. Shutdown may entail closing // any active sockets, database handles, stopping goroutines, etc. // // This is a part of the WalletController interface. func (b *BtcWallet) Stop() error { b.wallet.Stop() b.wallet.WaitForShutdown() b.chain.Stop() return nil } // ConfirmedBalance returns the sum of all the wallet's unspent outputs that // have at least confs confirmations. If confs is set to zero, then all unspent // outputs, including those currently in the mempool will be included in the // final sum. // // This is a part of the WalletController interface. func (b *BtcWallet) ConfirmedBalance(confs int32) (btcutil.Amount, error) { var balance btcutil.Amount witnessOutputs, err := b.ListUnspentWitness(confs, math.MaxInt32) if err != nil { return 0, err } for _, witnessOutput := range witnessOutputs { balance += witnessOutput.Value } return balance, nil } // NewAddress returns the next external or internal address for the wallet // dictated by the value of the `change` parameter. If change is true, then an // internal address will be returned, otherwise an external address should be // returned. // // This is a part of the WalletController interface. func (b *BtcWallet) NewAddress(t lnwallet.AddressType, change bool) (btcutil.Address, error) { var keyScope waddrmgr.KeyScope switch t { case lnwallet.WitnessPubKey: keyScope = waddrmgr.KeyScopeBIP0084 case lnwallet.NestedWitnessPubKey: keyScope = waddrmgr.KeyScopeBIP0049Plus default: return nil, fmt.Errorf("unknown address type") } if change { return b.wallet.NewChangeAddress(defaultAccount, keyScope) } return b.wallet.NewAddress(defaultAccount, keyScope) } // LastUnusedAddress returns the last *unused* address known by the wallet. An // address is unused if it hasn't received any payments. This can be useful in // UIs in order to continually show the "freshest" address without having to // worry about "address inflation" caused by continual refreshing. Similar to // NewAddress it can derive a specified address type, and also optionally a // change address. func (b *BtcWallet) LastUnusedAddress(addrType lnwallet.AddressType) ( btcutil.Address, error) { var keyScope waddrmgr.KeyScope switch addrType { case lnwallet.WitnessPubKey: keyScope = waddrmgr.KeyScopeBIP0084 case lnwallet.NestedWitnessPubKey: keyScope = waddrmgr.KeyScopeBIP0049Plus default: return nil, fmt.Errorf("unknown address type") } return b.wallet.CurrentAddress(defaultAccount, keyScope) } // IsOurAddress checks if the passed address belongs to this wallet // // This is a part of the WalletController interface. func (b *BtcWallet) IsOurAddress(a btcutil.Address) bool { result, err := b.wallet.HaveAddress(a) return result && (err == nil) } // SendOutputs funds, signs, and broadcasts a Bitcoin transaction paying out to // the specified outputs. In the case the wallet has insufficient funds, or the // outputs are non-standard, a non-nil error will be returned. // // NOTE: This method requires the global coin selection lock to be held. // // This is a part of the WalletController interface. func (b *BtcWallet) SendOutputs(outputs []*wire.TxOut, feeRate chainfee.SatPerKWeight, label string) (*wire.MsgTx, error) { // Convert our fee rate from sat/kw to sat/kb since it's required by // SendOutputs. feeSatPerKB := btcutil.Amount(feeRate.FeePerKVByte()) // Sanity check outputs. if len(outputs) < 1 { return nil, lnwallet.ErrNoOutputs } return b.wallet.SendOutputs( outputs, defaultAccount, 1, feeSatPerKB, label, ) } // CreateSimpleTx creates a Bitcoin transaction paying to the specified // outputs. The transaction is not broadcasted to the network, but a new change // address might be created in the wallet database. In the case the wallet has // insufficient funds, or the outputs are non-standard, an error should be // returned. This method also takes the target fee expressed in sat/kw that // should be used when crafting the transaction. // // NOTE: The dryRun argument can be set true to create a tx that doesn't alter // the database. A tx created with this set to true SHOULD NOT be broadcasted. // // NOTE: This method requires the global coin selection lock to be held. // // This is a part of the WalletController interface. func (b *BtcWallet) CreateSimpleTx(outputs []*wire.TxOut, feeRate chainfee.SatPerKWeight, dryRun bool) (*txauthor.AuthoredTx, error) { // The fee rate is passed in using units of sat/kw, so we'll convert // this to sat/KB as the CreateSimpleTx method requires this unit. feeSatPerKB := btcutil.Amount(feeRate.FeePerKVByte()) // Sanity check outputs. if len(outputs) < 1 { return nil, lnwallet.ErrNoOutputs } for _, output := range outputs { // When checking an output for things like dusty-ness, we'll // use the default mempool relay fee rather than the target // effective fee rate to ensure accuracy. Otherwise, we may // mistakenly mark small-ish, but not quite dust output as // dust. err := txrules.CheckOutput( output, txrules.DefaultRelayFeePerKb, ) if err != nil { return nil, err } } return b.wallet.CreateSimpleTx(defaultAccount, outputs, 1, feeSatPerKB, dryRun) } // LockOutpoint marks an outpoint as locked meaning it will no longer be deemed // as eligible for coin selection. Locking outputs are utilized in order to // avoid race conditions when selecting inputs for usage when funding a // channel. // // NOTE: This method requires the global coin selection lock to be held. // // This is a part of the WalletController interface. func (b *BtcWallet) LockOutpoint(o wire.OutPoint) { b.wallet.LockOutpoint(o) } // UnlockOutpoint unlocks a previously locked output, marking it eligible for // coin selection. // // NOTE: This method requires the global coin selection lock to be held. // // This is a part of the WalletController interface. func (b *BtcWallet) UnlockOutpoint(o wire.OutPoint) { b.wallet.UnlockOutpoint(o) } // LeaseOutput locks an output to the given ID, preventing it from being // available for any future coin selection attempts. The absolute time of the // lock's expiration is returned. The expiration of the lock can be extended by // successive invocations of this call. Outputs can be unlocked before their // expiration through `ReleaseOutput`. // // If the output is not known, wtxmgr.ErrUnknownOutput is returned. If the // output has already been locked to a different ID, then // wtxmgr.ErrOutputAlreadyLocked is returned. // // NOTE: This method requires the global coin selection lock to be held. func (b *BtcWallet) LeaseOutput(id wtxmgr.LockID, op wire.OutPoint) (time.Time, error) { // Make sure we don't attempt to double lock an output that's been // locked by the in-memory implementation. if b.wallet.LockedOutpoint(op) { return time.Time{}, wtxmgr.ErrOutputAlreadyLocked } return b.wallet.LeaseOutput(id, op) } // ReleaseOutput unlocks an output, allowing it to be available for coin // selection if it remains unspent. The ID should match the one used to // originally lock the output. // // NOTE: This method requires the global coin selection lock to be held. func (b *BtcWallet) ReleaseOutput(id wtxmgr.LockID, op wire.OutPoint) error { return b.wallet.ReleaseOutput(id, op) } // ListUnspentWitness returns a slice of all the unspent outputs the wallet // controls which pay to witness programs either directly or indirectly. // // NOTE: This method requires the global coin selection lock to be held. // // This is a part of the WalletController interface. func (b *BtcWallet) ListUnspentWitness(minConfs, maxConfs int32) ( []*lnwallet.Utxo, error) { // First, grab all the unfiltered currently unspent outputs. unspentOutputs, err := b.wallet.ListUnspent(minConfs, maxConfs, nil) if err != nil { return nil, err } // Next, we'll run through all the regular outputs, only saving those // which are p2wkh outputs or a p2wsh output nested within a p2sh output. witnessOutputs := make([]*lnwallet.Utxo, 0, len(unspentOutputs)) for _, output := range unspentOutputs { pkScript, err := hex.DecodeString(output.ScriptPubKey) if err != nil { return nil, err } addressType := lnwallet.UnknownAddressType if txscript.IsPayToWitnessPubKeyHash(pkScript) { addressType = lnwallet.WitnessPubKey } else if txscript.IsPayToScriptHash(pkScript) { // TODO(roasbeef): This assumes all p2sh outputs returned by the // wallet are nested p2pkh. We can't check the redeem script because // the btcwallet service does not include it. addressType = lnwallet.NestedWitnessPubKey } if addressType == lnwallet.WitnessPubKey || addressType == lnwallet.NestedWitnessPubKey { txid, err := chainhash.NewHashFromStr(output.TxID) if err != nil { return nil, err } // We'll ensure we properly convert the amount given in // BTC to satoshis. amt, err := btcutil.NewAmount(output.Amount) if err != nil { return nil, err } utxo := &lnwallet.Utxo{ AddressType: addressType, Value: amt, PkScript: pkScript, OutPoint: wire.OutPoint{ Hash: *txid, Index: output.Vout, }, Confirmations: output.Confirmations, } witnessOutputs = append(witnessOutputs, utxo) } } return witnessOutputs, nil } // PublishTransaction performs cursory validation (dust checks, etc), then // finally broadcasts the passed transaction to the Bitcoin network. If // publishing the transaction fails, an error describing the reason is returned // (currently ErrDoubleSpend). If the transaction is already published to the // network (either in the mempool or chain) no error will be returned. func (b *BtcWallet) PublishTransaction(tx *wire.MsgTx, label string) error { if err := b.wallet.PublishTransaction(tx, label); err != nil { // If we failed to publish the transaction, check whether we // got an error of known type. switch err.(type) { // If the wallet reports a double spend, convert it to our // internal ErrDoubleSpend and return. case *base.ErrDoubleSpend: return lnwallet.ErrDoubleSpend // If the wallet reports a replacement error, return // ErrDoubleSpend, as we currently are never attempting to // replace transactions. case *base.ErrReplacement: return lnwallet.ErrDoubleSpend default: return err } } return nil } // LabelTransaction adds a label to a transaction. If the tx already // has a label, this call will fail unless the overwrite parameter // is set. Labels must not be empty, and they are limited to 500 chars. // // Note: it is part of the WalletController interface. func (b *BtcWallet) LabelTransaction(hash chainhash.Hash, label string, overwrite bool) error { return b.wallet.LabelTransaction(hash, label, overwrite) } // extractBalanceDelta extracts the net balance delta from the PoV of the // wallet given a TransactionSummary. func extractBalanceDelta( txSummary base.TransactionSummary, tx *wire.MsgTx, ) (btcutil.Amount, error) { // For each input we debit the wallet's outflow for this transaction, // and for each output we credit the wallet's inflow for this // transaction. var balanceDelta btcutil.Amount for _, input := range txSummary.MyInputs { balanceDelta -= input.PreviousAmount } for _, output := range txSummary.MyOutputs { balanceDelta += btcutil.Amount(tx.TxOut[output.Index].Value) } return balanceDelta, nil } // minedTransactionsToDetails is a helper function which converts a summary // information about mined transactions to a TransactionDetail. func minedTransactionsToDetails( currentHeight int32, block base.Block, chainParams *chaincfg.Params, ) ([]*lnwallet.TransactionDetail, error) { details := make([]*lnwallet.TransactionDetail, 0, len(block.Transactions)) for _, tx := range block.Transactions { wireTx := &wire.MsgTx{} txReader := bytes.NewReader(tx.Transaction) if err := wireTx.Deserialize(txReader); err != nil { return nil, err } var destAddresses []btcutil.Address for _, txOut := range wireTx.TxOut { _, outAddresses, _, err := txscript.ExtractPkScriptAddrs( txOut.PkScript, chainParams, ) if err != nil { return nil, err } destAddresses = append(destAddresses, outAddresses...) } txDetail := &lnwallet.TransactionDetail{ Hash: *tx.Hash, NumConfirmations: currentHeight - block.Height + 1, BlockHash: block.Hash, BlockHeight: block.Height, Timestamp: block.Timestamp, TotalFees: int64(tx.Fee), DestAddresses: destAddresses, RawTx: tx.Transaction, Label: tx.Label, } balanceDelta, err := extractBalanceDelta(tx, wireTx) if err != nil { return nil, err } txDetail.Value = balanceDelta details = append(details, txDetail) } return details, nil } // unminedTransactionsToDetail is a helper function which converts a summary // for an unconfirmed transaction to a transaction detail. func unminedTransactionsToDetail( summary base.TransactionSummary, chainParams *chaincfg.Params, ) (*lnwallet.TransactionDetail, error) { wireTx := &wire.MsgTx{} txReader := bytes.NewReader(summary.Transaction) if err := wireTx.Deserialize(txReader); err != nil { return nil, err } var destAddresses []btcutil.Address for _, txOut := range wireTx.TxOut { _, outAddresses, _, err := txscript.ExtractPkScriptAddrs(txOut.PkScript, chainParams) if err != nil { return nil, err } destAddresses = append(destAddresses, outAddresses...) } txDetail := &lnwallet.TransactionDetail{ Hash: *summary.Hash, TotalFees: int64(summary.Fee), Timestamp: summary.Timestamp, DestAddresses: destAddresses, RawTx: summary.Transaction, Label: summary.Label, } balanceDelta, err := extractBalanceDelta(summary, wireTx) if err != nil { return nil, err } txDetail.Value = balanceDelta return txDetail, nil } // ListTransactionDetails returns a list of all transactions which are // relevant to the wallet. It takes inclusive start and end height to allow // paginated queries. Unconfirmed transactions can be included in the query // by providing endHeight = UnconfirmedHeight (= -1). // // This is a part of the WalletController interface. func (b *BtcWallet) ListTransactionDetails(startHeight, endHeight int32) ([]*lnwallet.TransactionDetail, error) { // Grab the best block the wallet knows of, we'll use this to calculate // # of confirmations shortly below. bestBlock := b.wallet.Manager.SyncedTo() currentHeight := bestBlock.Height // We'll attempt to find all transactions from start to end height. start := base.NewBlockIdentifierFromHeight(startHeight) stop := base.NewBlockIdentifierFromHeight(endHeight) txns, err := b.wallet.GetTransactions(start, stop, nil) if err != nil { return nil, err } txDetails := make([]*lnwallet.TransactionDetail, 0, len(txns.MinedTransactions)+len(txns.UnminedTransactions)) // For both confirmed and unconfirmed transactions, create a // TransactionDetail which re-packages the data returned by the base // wallet. for _, blockPackage := range txns.MinedTransactions { details, err := minedTransactionsToDetails( currentHeight, blockPackage, b.netParams, ) if err != nil { return nil, err } txDetails = append(txDetails, details...) } for _, tx := range txns.UnminedTransactions { detail, err := unminedTransactionsToDetail(tx, b.netParams) if err != nil { return nil, err } txDetails = append(txDetails, detail) } return txDetails, nil } // txSubscriptionClient encapsulates the transaction notification client from // the base wallet. Notifications received from the client will be proxied over // two distinct channels. type txSubscriptionClient struct { txClient base.TransactionNotificationsClient confirmed chan *lnwallet.TransactionDetail unconfirmed chan *lnwallet.TransactionDetail w *base.Wallet wg sync.WaitGroup quit chan struct{} } // ConfirmedTransactions returns a channel which will be sent on as new // relevant transactions are confirmed. // // This is part of the TransactionSubscription interface. func (t *txSubscriptionClient) ConfirmedTransactions() chan *lnwallet.TransactionDetail { return t.confirmed } // UnconfirmedTransactions returns a channel which will be sent on as // new relevant transactions are seen within the network. // // This is part of the TransactionSubscription interface. func (t *txSubscriptionClient) UnconfirmedTransactions() chan *lnwallet.TransactionDetail { return t.unconfirmed } // Cancel finalizes the subscription, cleaning up any resources allocated. // // This is part of the TransactionSubscription interface. func (t *txSubscriptionClient) Cancel() { close(t.quit) t.wg.Wait() t.txClient.Done() } // notificationProxier proxies the notifications received by the underlying // wallet's notification client to a higher-level TransactionSubscription // client. func (t *txSubscriptionClient) notificationProxier() { out: for { select { case txNtfn := <-t.txClient.C: // TODO(roasbeef): handle detached blocks currentHeight := t.w.Manager.SyncedTo().Height // Launch a goroutine to re-package and send // notifications for any newly confirmed transactions. go func() { for _, block := range txNtfn.AttachedBlocks { details, err := minedTransactionsToDetails(currentHeight, block, t.w.ChainParams()) if err != nil { continue } for _, d := range details { select { case t.confirmed <- d: case <-t.quit: return } } } }() // Launch a goroutine to re-package and send // notifications for any newly unconfirmed transactions. go func() { for _, tx := range txNtfn.UnminedTransactions { detail, err := unminedTransactionsToDetail( tx, t.w.ChainParams(), ) if err != nil { continue } select { case t.unconfirmed <- detail: case <-t.quit: return } } }() case <-t.quit: break out } } t.wg.Done() } // SubscribeTransactions returns a TransactionSubscription client which // is capable of receiving async notifications as new transactions // related to the wallet are seen within the network, or found in // blocks. // // This is a part of the WalletController interface. func (b *BtcWallet) SubscribeTransactions() (lnwallet.TransactionSubscription, error) { walletClient := b.wallet.NtfnServer.TransactionNotifications() txClient := &txSubscriptionClient{ txClient: walletClient, confirmed: make(chan *lnwallet.TransactionDetail), unconfirmed: make(chan *lnwallet.TransactionDetail), w: b.wallet, quit: make(chan struct{}), } txClient.wg.Add(1) go txClient.notificationProxier() return txClient, nil } // IsSynced returns a boolean indicating if from the PoV of the wallet, it has // fully synced to the current best block in the main chain. // // This is a part of the WalletController interface. func (b *BtcWallet) IsSynced() (bool, int64, error) { // Grab the best chain state the wallet is currently aware of. syncState := b.wallet.Manager.SyncedTo() // We'll also extract the current best wallet timestamp so the caller // can get an idea of where we are in the sync timeline. bestTimestamp := syncState.Timestamp.Unix() // Next, query the chain backend to grab the info about the tip of the // main chain. bestHash, bestHeight, err := b.cfg.ChainSource.GetBestBlock() if err != nil { return false, 0, err } // If the wallet hasn't yet fully synced to the node's best chain tip, // then we're not yet fully synced. if syncState.Height < bestHeight || !b.wallet.ChainSynced() { return false, bestTimestamp, nil } // If the wallet is on par with the current best chain tip, then we // still may not yet be synced as the chain backend may still be // catching up to the main chain. So we'll grab the block header in // order to make a guess based on the current time stamp. blockHeader, err := b.cfg.ChainSource.GetBlockHeader(bestHash) if err != nil { return false, 0, err } // If the timestamp on the best header is more than 2 hours in the // past, then we're not yet synced. minus24Hours := time.Now().Add(-2 * time.Hour) if blockHeader.Timestamp.Before(minus24Hours) { return false, bestTimestamp, nil } return true, bestTimestamp, nil } // GetRecoveryInfo returns a boolean indicating whether the wallet is started // in recovery mode. It also returns a float64, ranging from 0 to 1, // representing the recovery progress made so far. // // This is a part of the WalletController interface. func (b *BtcWallet) GetRecoveryInfo() (bool, float64, error) { isRecoveryMode := true progress := float64(0) // A zero value in RecoveryWindow indicates there is no trigger of // recovery mode. if b.cfg.RecoveryWindow == 0 { isRecoveryMode = false return isRecoveryMode, progress, nil } // Query the wallet's birthday block height from db. var birthdayBlock waddrmgr.BlockStamp err := walletdb.View(b.db, func(tx walletdb.ReadTx) error { var err error addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey) birthdayBlock, _, err = b.wallet.Manager.BirthdayBlock(addrmgrNs) if err != nil { return err } return nil }) if err != nil { // The wallet won't start until the backend is synced, thus the birthday // block won't be set and this particular error will be returned. We'll // catch this error and return a progress of 0 instead. if waddrmgr.IsError(err, waddrmgr.ErrBirthdayBlockNotSet) { return isRecoveryMode, progress, nil } return isRecoveryMode, progress, err } // Grab the best chain state the wallet is currently aware of. syncState := b.wallet.Manager.SyncedTo() // Next, query the chain backend to grab the info about the tip of the // main chain. // // NOTE: The actual recovery process is handled by the btcsuite/btcwallet. // The process purposefully doesn't update the best height. It might create // a small difference between the height queried here and the height used // in the recovery process, ie, the bestHeight used here might be greater, // showing the recovery being unfinished while it's actually done. However, // during a wallet rescan after the recovery, the wallet's synced height // will catch up and this won't be an issue. _, bestHeight, err := b.cfg.ChainSource.GetBestBlock() if err != nil { return isRecoveryMode, progress, err } // The birthday block height might be greater than the current synced height // in a newly restored wallet, and might be greater than the chain tip if a // rollback happens. In that case, we will return zero progress here. if syncState.Height < birthdayBlock.Height || bestHeight < birthdayBlock.Height { return isRecoveryMode, progress, nil } // progress is the ratio of the [number of blocks processed] over the [total // number of blocks] needed in a recovery mode, ranging from 0 to 1, in // which, // - total number of blocks is the current chain's best height minus the // wallet's birthday height plus 1. // - number of blocks processed is the wallet's synced height minus its // birthday height plus 1. // - If the wallet is born very recently, the bestHeight can be equal to // the birthdayBlock.Height, and it will recovery instantly. progress = float64(syncState.Height-birthdayBlock.Height+1) / float64(bestHeight-birthdayBlock.Height+1) return isRecoveryMode, progress, nil }