lbcwallet/wallet/createtx.go
Oliver Gugger f07fdfb6b9
wallet: refactor txToOutputs to use walletdb.Update
To make sure we don't create any manual DB transactions, we refactor the
txToOutputs method to use walletdb.Update and the new
walletdb.ErrDryRunRollBack error for making sure a rollback is issued.
2021-07-23 12:49:38 +02:00

433 lines
13 KiB
Go

// Copyright (c) 2013-2017 The btcsuite developers
// Copyright (c) 2015-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package wallet
import (
"fmt"
"math/rand"
"sort"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/txscript"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
"github.com/btcsuite/btcwallet/waddrmgr"
"github.com/btcsuite/btcwallet/wallet/txauthor"
"github.com/btcsuite/btcwallet/wallet/txsizes"
"github.com/btcsuite/btcwallet/walletdb"
"github.com/btcsuite/btcwallet/wtxmgr"
)
// byAmount defines the methods needed to satisify sort.Interface to
// sort credits by their output amount.
type byAmount []wtxmgr.Credit
func (s byAmount) Len() int { return len(s) }
func (s byAmount) Less(i, j int) bool { return s[i].Amount < s[j].Amount }
func (s byAmount) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func makeInputSource(eligible []wtxmgr.Credit) txauthor.InputSource {
// Current inputs and their total value. These are closed over by the
// returned input source and reused across multiple calls.
currentTotal := btcutil.Amount(0)
currentInputs := make([]*wire.TxIn, 0, len(eligible))
currentScripts := make([][]byte, 0, len(eligible))
currentInputValues := make([]btcutil.Amount, 0, len(eligible))
return func(target btcutil.Amount) (btcutil.Amount, []*wire.TxIn,
[]btcutil.Amount, [][]byte, error) {
for currentTotal < target && len(eligible) != 0 {
nextCredit := &eligible[0]
eligible = eligible[1:]
nextInput := wire.NewTxIn(&nextCredit.OutPoint, nil, nil)
currentTotal += nextCredit.Amount
currentInputs = append(currentInputs, nextInput)
currentScripts = append(currentScripts, nextCredit.PkScript)
currentInputValues = append(currentInputValues, nextCredit.Amount)
}
return currentTotal, currentInputs, currentInputValues, currentScripts, nil
}
}
// secretSource is an implementation of txauthor.SecretSource for the wallet's
// address manager.
type secretSource struct {
*waddrmgr.Manager
addrmgrNs walletdb.ReadBucket
}
func (s secretSource) GetKey(addr btcutil.Address) (*btcec.PrivateKey, bool, error) {
ma, err := s.Address(s.addrmgrNs, addr)
if err != nil {
return nil, false, err
}
mpka, ok := ma.(waddrmgr.ManagedPubKeyAddress)
if !ok {
e := fmt.Errorf("managed address type for %v is `%T` but "+
"want waddrmgr.ManagedPubKeyAddress", addr, ma)
return nil, false, e
}
privKey, err := mpka.PrivKey()
if err != nil {
return nil, false, err
}
return privKey, ma.Compressed(), nil
}
func (s secretSource) GetScript(addr btcutil.Address) ([]byte, error) {
ma, err := s.Address(s.addrmgrNs, addr)
if err != nil {
return nil, err
}
msa, ok := ma.(waddrmgr.ManagedScriptAddress)
if !ok {
e := fmt.Errorf("managed address type for %v is `%T` but "+
"want waddrmgr.ManagedScriptAddress", addr, ma)
return nil, e
}
return msa.Script()
}
// txToOutputs creates a signed transaction which includes each output from
// outputs. Previous outputs to redeem are chosen from the passed account's
// UTXO set and minconf policy. An additional output may be added to return
// change to the wallet. This output will have an address generated from the
// given key scope and account. If a key scope is not specified, the address
// will always be generated from the P2WKH key scope. An appropriate fee is
// included based on the wallet's current relay fee. The wallet must be
// unlocked to create 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 will intentionally have no
// input scripts added and SHOULD NOT be broadcasted.
func (w *Wallet) txToOutputs(outputs []*wire.TxOut, keyScope *waddrmgr.KeyScope,
account uint32, minconf int32, feeSatPerKb btcutil.Amount,
coinSelectionStrategy CoinSelectionStrategy, dryRun bool) (
*txauthor.AuthoredTx, error) {
chainClient, err := w.requireChainClient()
if err != nil {
return nil, err
}
// Get current block's height and hash.
bs, err := chainClient.BlockStamp()
if err != nil {
return nil, err
}
var tx *txauthor.AuthoredTx
err = walletdb.Update(w.db, func(dbtx walletdb.ReadWriteTx) error {
addrmgrNs, changeSource, err := w.addrMgrWithChangeSource(
dbtx, keyScope, account,
)
if err != nil {
return err
}
eligible, err := w.findEligibleOutputs(
dbtx, keyScope, account, minconf, bs,
)
if err != nil {
return err
}
var inputSource txauthor.InputSource
switch coinSelectionStrategy {
// Pick largest outputs first.
case CoinSelectionLargest:
sort.Sort(sort.Reverse(byAmount(eligible)))
inputSource = makeInputSource(eligible)
// Select coins at random. This prevents the creation of ever
// smaller utxos over time that may never become economical to
// spend.
case CoinSelectionRandom:
// Skip inputs that do not raise the total transaction
// output value at the requested fee rate.
var positivelyYielding []wtxmgr.Credit
for _, output := range eligible {
output := output
if !inputYieldsPositively(&output, feeSatPerKb) {
continue
}
positivelyYielding = append(
positivelyYielding, output,
)
}
rand.Shuffle(len(positivelyYielding), func(i, j int) {
positivelyYielding[i], positivelyYielding[j] =
positivelyYielding[j], positivelyYielding[i]
})
inputSource = makeInputSource(positivelyYielding)
}
tx, err = txauthor.NewUnsignedTransaction(
outputs, feeSatPerKb, inputSource, changeSource,
)
if err != nil {
return err
}
// Randomize change position, if change exists, before signing.
// This doesn't affect the serialize size, so the change amount
// will still be valid.
if tx.ChangeIndex >= 0 {
tx.RandomizeChangePosition()
}
// If a dry run was requested, we return now before adding the
// input scripts, and don't commit the database transaction.
// By returning an error, we make sure the walletdb.Update call
// rolls back the transaction. But we'll react to this specific
// error outside of the DB transaction so we can still return
// the produced chain TX.
if dryRun {
return walletdb.ErrDryRunRollBack
}
// Before committing the transaction, we'll sign our inputs. If
// the inputs are part of a watch-only account, there's no
// private key information stored, so we'll skip signing such.
var watchOnly bool
if keyScope == nil {
// If a key scope wasn't specified, then coin selection
// was performed from the default wallet accounts
// (NP2WKH, P2WKH), so any key scope provided doesn't
// impact the result of this call.
watchOnly, err = w.Manager.IsWatchOnlyAccount(
addrmgrNs, waddrmgr.KeyScopeBIP0084, account,
)
} else {
watchOnly, err = w.Manager.IsWatchOnlyAccount(
addrmgrNs, *keyScope, account,
)
}
if err != nil {
return err
}
if !watchOnly {
err = tx.AddAllInputScripts(
secretSource{w.Manager, addrmgrNs},
)
if err != nil {
return err
}
err = validateMsgTx(
tx.Tx, tx.PrevScripts, tx.PrevInputValues,
)
if err != nil {
return err
}
}
if tx.ChangeIndex >= 0 && account == waddrmgr.ImportedAddrAccount {
changeAmount := btcutil.Amount(
tx.Tx.TxOut[tx.ChangeIndex].Value,
)
log.Warnf("Spend from imported account produced "+
"change: moving %v from imported account into "+
"default account.", changeAmount)
}
// Finally, we'll request the backend to notify us of the
// transaction that pays to the change address, if there is one,
// when it confirms.
if tx.ChangeIndex >= 0 {
changePkScript := tx.Tx.TxOut[tx.ChangeIndex].PkScript
_, addrs, _, err := txscript.ExtractPkScriptAddrs(
changePkScript, w.chainParams,
)
if err != nil {
return err
}
if err := chainClient.NotifyReceived(addrs); err != nil {
return err
}
}
return nil
})
if err != nil && err != walletdb.ErrDryRunRollBack {
return nil, err
}
return tx, nil
}
func (w *Wallet) findEligibleOutputs(dbtx walletdb.ReadTx,
keyScope *waddrmgr.KeyScope, account uint32, minconf int32,
bs *waddrmgr.BlockStamp) ([]wtxmgr.Credit, error) {
addrmgrNs := dbtx.ReadBucket(waddrmgrNamespaceKey)
txmgrNs := dbtx.ReadBucket(wtxmgrNamespaceKey)
unspent, err := w.TxStore.UnspentOutputs(txmgrNs)
if err != nil {
return nil, err
}
// TODO: Eventually all of these filters (except perhaps output locking)
// should be handled by the call to UnspentOutputs (or similar).
// Because one of these filters requires matching the output script to
// the desired account, this change depends on making wtxmgr a waddrmgr
// dependency and requesting unspent outputs for a single account.
eligible := make([]wtxmgr.Credit, 0, len(unspent))
for i := range unspent {
output := &unspent[i]
// Only include this output if it meets the required number of
// confirmations. Coinbase transactions must have have reached
// maturity before their outputs may be spent.
if !confirmed(minconf, output.Height, bs.Height) {
continue
}
if output.FromCoinBase {
target := int32(w.chainParams.CoinbaseMaturity)
if !confirmed(target, output.Height, bs.Height) {
continue
}
}
// Locked unspent outputs are skipped.
if w.LockedOutpoint(output.OutPoint) {
continue
}
// Only include the output if it is associated with the passed
// account.
//
// TODO: Handle multisig outputs by determining if enough of the
// addresses are controlled.
_, addrs, _, err := txscript.ExtractPkScriptAddrs(
output.PkScript, w.chainParams)
if err != nil || len(addrs) != 1 {
continue
}
scopedMgr, addrAcct, err := w.Manager.AddrAccount(addrmgrNs, addrs[0])
if err != nil {
continue
}
if keyScope != nil && scopedMgr.Scope() != *keyScope {
continue
}
if addrAcct != account {
continue
}
eligible = append(eligible, *output)
}
return eligible, nil
}
// inputYieldsPositively returns a boolean indicating whether this input yields
// positively if added to a transaction. This determination is based on the
// best-case added virtual size. For edge cases this function can return true
// while the input is yielding slightly negative as part of the final
// transaction.
func inputYieldsPositively(credit *wtxmgr.Credit, feeRatePerKb btcutil.Amount) bool {
inputSize := txsizes.GetMinInputVirtualSize(credit.PkScript)
inputFee := feeRatePerKb * btcutil.Amount(inputSize) / 1000
return inputFee < credit.Amount
}
// addrMgrWithChangeSource returns the address manager bucket and a change
// source that returns change addresses from said address manager. The change
// addresses will come from the specified key scope and account, unless a key
// scope is not specified. In that case, change addresses will always come from
// the P2WKH key scope.
func (w *Wallet) addrMgrWithChangeSource(dbtx walletdb.ReadWriteTx,
changeKeyScope *waddrmgr.KeyScope, account uint32) (
walletdb.ReadWriteBucket, *txauthor.ChangeSource, error) {
// Determine the address type for change addresses of the given account.
if changeKeyScope == nil {
changeKeyScope = &waddrmgr.KeyScopeBIP0084
}
addrType := waddrmgr.ScopeAddrMap[*changeKeyScope].InternalAddrType
// It's possible for the account to have an address schema override, so
// prefer that if it exists.
addrmgrNs := dbtx.ReadWriteBucket(waddrmgrNamespaceKey)
scopeMgr, err := w.Manager.FetchScopedKeyManager(*changeKeyScope)
if err != nil {
return nil, nil, err
}
accountInfo, err := scopeMgr.AccountProperties(addrmgrNs, account)
if err != nil {
return nil, nil, err
}
if accountInfo.AddrSchema != nil {
addrType = accountInfo.AddrSchema.InternalAddrType
}
// Compute the expected size of the script for the change address type.
var scriptSize int
switch addrType {
case waddrmgr.PubKeyHash:
scriptSize = txsizes.P2PKHPkScriptSize
case waddrmgr.NestedWitnessPubKey:
scriptSize = txsizes.NestedP2WPKHPkScriptSize
case waddrmgr.WitnessPubKey:
scriptSize = txsizes.P2WPKHPkScriptSize
}
newChangeScript := func() ([]byte, error) {
// Derive the change output script. As a hack to allow spending
// from the imported account, change addresses are created from
// account 0.
var (
changeAddr btcutil.Address
err error
)
if account == waddrmgr.ImportedAddrAccount {
changeAddr, err = w.newChangeAddress(
addrmgrNs, 0, *changeKeyScope,
)
} else {
changeAddr, err = w.newChangeAddress(
addrmgrNs, account, *changeKeyScope,
)
}
if err != nil {
return nil, err
}
return txscript.PayToAddrScript(changeAddr)
}
return addrmgrNs, &txauthor.ChangeSource{
ScriptSize: scriptSize,
NewScript: newChangeScript,
}, nil
}
// validateMsgTx verifies transaction input scripts for tx. All previous output
// scripts from outputs redeemed by the transaction, in the same order they are
// spent, must be passed in the prevScripts slice.
func validateMsgTx(tx *wire.MsgTx, prevScripts [][]byte, inputValues []btcutil.Amount) error {
hashCache := txscript.NewTxSigHashes(tx)
for i, prevScript := range prevScripts {
vm, err := txscript.NewEngine(prevScript, tx, i,
txscript.StandardVerifyFlags, nil, hashCache, int64(inputValues[i]))
if err != nil {
return fmt.Errorf("cannot create script engine: %s", err)
}
err = vm.Execute()
if err != nil {
return fmt.Errorf("cannot validate transaction: %s", err)
}
}
return nil
}