lbcwallet/wallet/createtx.go
Wilmer Paulino 60fce250f4
wallet: derive change addresses from the provided key scope
Previously, the wallet would determine the key scope to use for change
addresses by locating the one compatible with P2WPKH addresses, but this
wasn't always safe like in the case when multiple key scopes that
supported these addresses existed within the address manager, leading
the change address to be created outside of the intended key scope.
2020-03-30 15:30:53 -07:00

290 lines
9 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"
"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/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 {
// Pick largest outputs first. This is only done for compatibility with
// previous tx creation code, not because it's a good idea.
sort.Sort(sort.Reverse(byAmount(eligible)))
// 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 reedeem are chosen from the passed account's
// UTXO set and minconf policy. An additional output may be added to return
// change to the wallet. 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, account uint32,
minconf int32, feeSatPerKb btcutil.Amount, dryRun bool) (
tx *txauthor.AuthoredTx, err error) {
chainClient, err := w.requireChainClient()
if err != nil {
return nil, err
}
dbtx, err := w.db.BeginReadWriteTx()
if err != nil {
return nil, err
}
defer dbtx.Rollback()
addrmgrNs := dbtx.ReadWriteBucket(waddrmgrNamespaceKey)
// Get current block's height and hash.
bs, err := chainClient.BlockStamp()
if err != nil {
return nil, err
}
eligible, err := w.findEligibleOutputs(dbtx, account, minconf, bs)
if err != nil {
return nil, err
}
inputSource := makeInputSource(eligible)
changeSource := func() ([]byte, error) {
// Derive the change output script. We'll use the default key
// scope responsible for P2WPKH addresses to do so. As a hack to
// allow spending from the imported account, change addresses
// are created from account 0.
var changeAddr btcutil.Address
var err error
changeKeyScope := waddrmgr.KeyScopeBIP0084
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)
}
tx, err = txauthor.NewUnsignedTransaction(outputs, feeSatPerKb,
inputSource, changeSource)
if err != nil {
return nil, 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. The DB will be
// rolled back when this method returns to ensure the dry run didn't
// alter the DB in any way.
if dryRun {
return tx, nil
}
err = tx.AddAllInputScripts(secretSource{w.Manager, addrmgrNs})
if err != nil {
return nil, err
}
err = validateMsgTx(tx.Tx, tx.PrevScripts, tx.PrevInputValues)
if err != nil {
return nil, err
}
if err := dbtx.Commit(); err != nil {
return nil, 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 nil, err
}
if err := chainClient.NotifyReceived(addrs); err != nil {
return nil, err
}
}
return tx, nil
}
func (w *Wallet) findEligibleOutputs(dbtx walletdb.ReadTx, 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
// dependancy 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
}
_, addrAcct, err := w.Manager.AddrAccount(addrmgrNs, addrs[0])
if err != nil || addrAcct != account {
continue
}
eligible = append(eligible, *output)
}
return eligible, 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
}