// countP2SHSigOps returns the number of signature operations for all input
// transactions which are of the pay-to-script-hash type. This uses the
// precise, signature operation counting mechanism from btcscript which requires
// access to the input transaction scripts.
func countP2SHSigOps(tx *btcutil.Tx, isCoinBaseTx bool, txStore TxStore) (int, error) {
// Coinbase transactions have no interesting inputs.
if isCoinBaseTx {
return 0, nil
}
// Accumulate the number of signature operations in all transaction
// inputs.
msgTx := tx.MsgTx()
totalSigOps := 0
for _, txIn := range msgTx.TxIn {
// Ensure the referenced input transaction is available.
txInHash := &txIn.PreviousOutpoint.Hash
originTx, exists := txStore[*txInHash]
if !exists || originTx.Err != nil || originTx.Tx == nil {
str := fmt.Sprintf("unable to find input transaction "+
"%v referenced from transaction %v", txInHash,
tx.Sha())
return 0, RuleError(str)
}
originMsgTx := originTx.Tx.MsgTx()
// Ensure the output index in the referenced transaction is
// available.
originTxIndex := txIn.PreviousOutpoint.Index
if originTxIndex >= uint32(len(originMsgTx.TxOut)) {
str := fmt.Sprintf("out of bounds input index %d in "+
"transaction %v referenced from transaction %v",
originTxIndex, txInHash, tx.Sha())
return 0, RuleError(str)
}
// We're only interested in pay-to-script-hash types, so skip
// this input if it's not one.
pkScript := originMsgTx.TxOut[originTxIndex].PkScript
if !btcscript.IsPayToScriptHash(pkScript) {
continue
}
// Count the precise number of signature operations in the
// referenced public key script.
sigScript := txIn.SignatureScript
numSigOps := btcscript.GetPreciseSigOpCount(sigScript, pkScript,
true)
// We could potentially overflow the accumulator so check for
// overflow.
lastSigOps := totalSigOps
totalSigOps += numSigOps
if totalSigOps < lastSigOps {
str := fmt.Sprintf("the public key script from "+
"output index %d in transaction %v contains "+
"too many signature operations - overflow",
originTxIndex, txInHash)
return 0, RuleError(str)
}
}
return totalSigOps, nil
}
// checkSerializedHeight checks if the signature script in the passed
// transaction starts with the serialized block height of wantHeight.
func checkSerializedHeight(coinbaseTx *btcutil.Tx, wantHeight int64) error {
sigScript := coinbaseTx.MsgTx().TxIn[0].SignatureScript
if len(sigScript) < 1 {
str := "the coinbase signature script for blocks of " +
"version %d or greater must start with the " +
"length of the serialized block height"
str = fmt.Sprintf(str, serializedHeightVersion)
return RuleError(str)
}
serializedLen := int(sigScript[0])
if len(sigScript[1:]) < serializedLen {
str := "the coinbase signature script for blocks of " +
"version %d or greater must start with the " +
"serialized block height"
str = fmt.Sprintf(str, serializedLen)
return RuleError(str)
}
serializedHeightBytes := make([]byte, 8, 8)
copy(serializedHeightBytes, sigScript[1:serializedLen+1])
serializedHeight := binary.LittleEndian.Uint64(serializedHeightBytes)
if int64(serializedHeight) != wantHeight {
str := fmt.Sprintf("the coinbase signature script serialized "+
"block height is %d when %d was expected",
serializedHeight, wantHeight)
return RuleError(str)
}
return nil
}
// IsFinalizedTransaction determines whether or not a transaction is finalized.
func IsFinalizedTransaction(tx *btcutil.Tx, blockHeight int64, blockTime time.Time) bool {
msgTx := tx.MsgTx()
// Lock time of zero means the transaction is finalized.
lockTime := msgTx.LockTime
if lockTime == 0 {
return true
}
// The lock time field of a transaction is either a block height at
// which the transaction is finalized or a timestamp depending on if the
// value is before the lockTimeThreshold. When it is under the
// threshold it is a block height.
blockTimeOrHeight := int64(0)
if lockTime < lockTimeThreshold {
blockTimeOrHeight = blockHeight
} else {
blockTimeOrHeight = blockTime.Unix()
}
if int64(lockTime) < blockTimeOrHeight {
return true
}
// At this point, the transaction's lock time hasn't occured yet, but
// the transaction might still be finalized if the sequence number
// for all transaction inputs is maxed out.
for _, txIn := range msgTx.TxIn {
if txIn.Sequence != math.MaxUint32 {
return false
}
}
return true
}
// ValidateTransactionScripts validates the scripts for the passed transaction
// using multiple goroutines.
func ValidateTransactionScripts(tx *btcutil.Tx, txStore TxStore, flags btcscript.ScriptFlags) error {
// Collect all of the transaction inputs and required information for
// validation.
txIns := tx.MsgTx().TxIn
txValItems := make([]*txValidateItem, 0, len(txIns))
for txInIdx, txIn := range txIns {
// Skip coinbases.
if txIn.PreviousOutpoint.Index == math.MaxUint32 {
continue
}
txVI := &txValidateItem{
txInIndex: txInIdx,
txIn: txIn,
tx: tx,
}
txValItems = append(txValItems, txVI)
}
// Validate all of the inputs.
validator := newTxValidator(txStore, flags)
if err := validator.Validate(txValItems); err != nil {
return err
}
return nil
}
// calcMinRelayFee retuns the minimum transaction fee required for the passed
// transaction to be accepted into the memory pool and relayed.
func calcMinRelayFee(tx *btcutil.Tx) int64 {
// Most miners allow a free transaction area in blocks they mine to go
// alongside the area used for high-priority transactions as well as
// transactions with fees. A transaction size of up to 1000 bytes is
// considered safe to go into this section. Further, the minimum fee
// calculated below on its own would encourage several small
// transactions to avoid fees rather than one single larger transaction
// which is more desirable. Therefore, as long as the size of the
// transaction does not exceeed 1000 less than the reserved space for
// high-priority transactions, don't require a fee for it.
serializedLen := int64(tx.MsgTx().SerializeSize())
if serializedLen < (defaultBlockPrioritySize - 1000) {
return 0
}
// Calculate the minimum fee for a transaction to be allowed into the
// mempool and relayed by scaling the base fee (which is the minimum
// free transaction relay fee). minTxRelayFee is in Satoshi/KB, so
// divide the transaction size by 1000 to convert to kilobytes. Also,
// integer division is used so fees only increase on full kilobyte
// boundaries.
minFee := (1 + serializedLen/1000) * minTxRelayFee
// Set the minimum fee to the maximum possible value if the calculated
// fee is not in the valid range for monetary amounts.
if minFee < 0 || minFee > btcutil.MaxSatoshi {
minFee = btcutil.MaxSatoshi
}
return minFee
}
// calcPriority returns a transaction priority given a transaction and the sum
// of each of its input values multiplied by their age (# of confirmations).
// Thus, the final formula for the priority is:
// sum(inputValue * inputAge) / adjustedTxSize
func calcPriority(tx *btcutil.Tx, serializedTxSize int, inputValueAge float64) float64 {
// In order to encourage spending multiple old unspent transaction
// outputs thereby reducing the total set, don't count the constant
// overhead for each input as well as enough bytes of the signature
// script to cover a pay-to-script-hash redemption with a compressed
// pubkey. This makes additional inputs free by boosting the priority
// of the transaction accordingly. No more incentive is given to avoid
// encouraging gaming future transactions through the use of junk
// outputs. This is the same logic used in the reference
// implementation.
//
// The constant overhead for a txin is 41 bytes since the previous
// outpoint is 36 bytes + 4 bytes for the sequence + 1 byte the
// signature script length.
//
// A compressed pubkey pay-to-script-hash redemption with a maximum len
// signature is of the form:
// [OP_DATA_73 <73-byte sig> + OP_DATA_35 + {OP_DATA_33
// <33 byte compresed pubkey> + OP_CHECKSIG}]
//
// Thus 1 + 73 + 1 + 1 + 33 + 1 = 110
overhead := 0
for _, txIn := range tx.MsgTx().TxIn {
// Max inputs + size can't possibly overflow here.
overhead += 41 + minInt(110, len(txIn.SignatureScript))
}
if overhead >= serializedTxSize {
return 0.0
}
return inputValueAge / float64(serializedTxSize-overhead)
}
// newBlockNotifyCheckTxIn is a helper function to iterate through
// each transaction input of a new block and perform any checks and
// notify listening frontends when necessary.
func (s *rpcServer) newBlockNotifyCheckTxIn(tx *btcutil.Tx) {
for wltNtfn, cxt := range s.ws.requests.m {
for _, txin := range tx.MsgTx().TxIn {
for op, id := range cxt.spentRequests {
if txin.PreviousOutpoint != op {
continue
}
reply := &btcjson.Reply{
Result: struct {
TxHash string `json:"txhash"`
Index uint32 `json:"index"`
}{
TxHash: op.Hash.String(),
Index: uint32(op.Index),
},
Error: nil,
Id: &id,
}
replyBytes, err := json.Marshal(reply)
if err != nil {
log.Errorf("RPCS: Unable to marshal spent notification: %v", err)
continue
}
wltNtfn <- replyBytes
s.ws.requests.RemoveSpentRequest(wltNtfn, &op)
}
}
}
}
func (u *unconfirmedStore) findDoubleSpend(tx *btcutil.Tx) *txRecord {
for _, input := range tx.MsgTx().TxIn {
if r, ok := u.previousOutpoints[input.PreviousOutpoint]; ok {
return r
}
}
return nil
}
// matchTxAndUpdate returns true if the bloom filter matches data within the
// passed transaction, otherwise false is returned. If the filter does match
// the passed transaction, it will also update the filter depending on the bloom
// update flags set via the loaded filter if needed.
//
// This function MUST be called with the filter lock held.
func (bf *Filter) matchTxAndUpdate(tx *btcutil.Tx) bool {
// Check if the filter matches the hash of the transaction.
// This is useful for finding transactions when they appear in a block.
matched := bf.matches(tx.Sha().Bytes())
// Check if the filter matches any data elements in the public key
// scripts of any of the outputs. When it does, add the outpoint that
// matched so transactions which spend from the matched transaction are
// also included in the filter. This removes the burden of updating the
// filter for this scenario from the client. It is also more efficient
// on the network since it avoids the need for another filteradd message
// from the client and avoids some potential races that could otherwise
// occur.
for i, txOut := range tx.MsgTx().TxOut {
pushedData, err := btcscript.PushedData(txOut.PkScript)
if err != nil {
continue
}
for _, data := range pushedData {
if !bf.matches(data) {
continue
}
matched = true
bf.maybeAddOutpoint(txOut.PkScript, tx.Sha(), uint32(i))
break
}
}
// Nothing more to do if a match has already been made.
if matched {
return true
}
// At this point, the transaction and none of the data elements in the
// public key scripts of its outputs matched.
// Check if the filter matches any outpoints this transaction spends or
// any any data elements in the signature scripts of any of the inputs.
for _, txin := range tx.MsgTx().TxIn {
if bf.matchesOutPoint(&txin.PreviousOutpoint) {
return true
}
pushedData, err := btcscript.PushedData(txin.SignatureScript)
if err != nil {
continue
}
for _, data := range pushedData {
if bf.matches(data) {
return true
}
}
}
return false
}
// findPreviousCredits searches for all unspent credits that make up the inputs
// for tx.
func (s *Store) findPreviousCredits(tx *btcutil.Tx) ([]Credit, error) {
type createdCredit struct {
credit Credit
err error
}
inputs := tx.MsgTx().TxIn
creditChans := make([]chan createdCredit, len(inputs))
for i, txIn := range inputs {
creditChans[i] = make(chan createdCredit)
go func(i int, op btcwire.OutPoint) {
key, ok := s.unspent[op]
if !ok {
// Does this input spend an unconfirmed output?
r, ok := s.unconfirmed.txs[op.Hash]
switch {
// Not an unconfirmed tx.
case !ok:
fallthrough
// Output isn't a credit.
case len(r.credits) <= int(op.Index):
fallthrough
// Output isn't a credit.
case r.credits[op.Index] == nil:
fallthrough
// Credit already spent.
case s.unconfirmed.spentUnconfirmed[op] != nil:
close(creditChans[i])
return
}
t := &TxRecord{BlockTxKey{BlockHeight: -1}, r, s}
c := Credit{t, op.Index}
creditChans[i] <- createdCredit{credit: c}
return
}
r, err := s.lookupBlockTx(key)
if err != nil {
creditChans[i] <- createdCredit{err: err}
return
}
t := &TxRecord{key, r, s}
c := Credit{t, op.Index}
creditChans[i] <- createdCredit{credit: c}
}(i, txIn.PreviousOutpoint)
}
spent := make([]Credit, 0, len(inputs))
for _, c := range creditChans {
cc, ok := <-c
if !ok {
continue
}
if cc.err != nil {
return nil, cc.err
}
spent = append(spent, cc.credit)
}
return spent, nil
}
// newBlockNotifyCheckTxOut is a helper function to iterate through
// each transaction output of a new block and perform any checks and
// notify listening frontends when necessary.
func (s *rpcServer) newBlockNotifyCheckTxOut(block *btcutil.Block, tx *btcutil.Tx, spent []bool) {
for wltNtfn, cxt := range s.ws.requests.m {
for i, txout := range tx.MsgTx().TxOut {
_, txaddrhash, err := btcscript.ScriptToAddrHash(txout.PkScript)
if err != nil {
log.Debug("Error getting payment address from tx; dropping any Tx notifications.")
break
}
for addr, id := range cxt.txRequests {
if !bytes.Equal(addr[:], txaddrhash) {
continue
}
blkhash, err := block.Sha()
if err != nil {
log.Error("Error getting block sha; dropping Tx notification.")
break
}
txaddr, err := btcutil.EncodeAddress(txaddrhash, s.server.btcnet)
if err != nil {
log.Error("Error encoding address; dropping Tx notification.")
break
}
reply := &btcjson.Reply{
Result: struct {
Sender string `json:"sender"`
Receiver string `json:"receiver"`
BlockHash string `json:"blockhash"`
Height int64 `json:"height"`
TxHash string `json:"txhash"`
Index uint32 `json:"index"`
Amount int64 `json:"amount"`
PkScript string `json:"pkscript"`
Spent bool `json:"spent"`
}{
Sender: "Unknown", // TODO(jrick)
Receiver: txaddr,
BlockHash: blkhash.String(),
Height: block.Height(),
TxHash: tx.Sha().String(),
Index: uint32(i),
Amount: txout.Value,
PkScript: btcutil.Base58Encode(txout.PkScript),
Spent: spent[i],
},
Error: nil,
Id: &id,
}
replyBytes, err := json.Marshal(reply)
if err != nil {
log.Errorf("RPCS: Unable to marshal tx notification: %v", err)
continue
}
wltNtfn <- replyBytes
}
}
}
}
// NotifyForTxOuts iterates through all outputs of a tx, performing any
// necessary notifications for wallets. If a non-nil block is passed,
// additional block information is passed with the notifications.
func (s *rpcServer) NotifyForTxOuts(tx *btcutil.Tx, block *btcutil.Block) {
// Nothing to do if nobody is listening for transaction notifications.
if len(s.ws.txNotifications) == 0 {
return
}
for i, txout := range tx.MsgTx().TxOut {
_, addrs, _, err := btcscript.ExtractPkScriptAddrs(
txout.PkScript, s.server.btcnet)
if err != nil {
continue
}
for _, addr := range addrs {
// Only support pay-to-pubkey-hash right now.
if _, ok := addr.(*btcutil.AddressPubKeyHash); !ok {
continue
}
encodedAddr := addr.EncodeAddress()
if idlist, ok := s.ws.txNotifications[encodedAddr]; ok {
for e := idlist.Front(); e != nil; e = e.Next() {
n := e.Value.(ntfnChan)
ntfn := &btcws.ProcessedTxNtfn{
Receiver: encodedAddr,
TxID: tx.Sha().String(),
TxOutIndex: uint32(i),
Amount: txout.Value,
PkScript: hex.EncodeToString(txout.PkScript),
// TODO(jrick): hardcoding unspent is WRONG and needs
// to be either calculated from other block txs, or dropped.
Spent: false,
}
if block != nil {
blkhash, err := block.Sha()
if err != nil {
rpcsLog.Error("Error getting block sha; dropping Tx notification")
break
}
ntfn.BlockHeight = int32(block.Height())
ntfn.BlockHash = blkhash.String()
ntfn.BlockIndex = tx.Index()
ntfn.BlockTime = block.MsgBlock().Header.Timestamp.Unix()
} else {
ntfn.BlockHeight = -1
ntfn.BlockIndex = -1
}
n <- ntfn
}
}
}
}
}
// checkPoolDoubleSpend checks whether or not the passed transaction is
// attempting to spend coins already spent by other transactions in the pool.
// Note it does not check for double spends against transactions already in the
// main chain.
//
// This function MUST be called with the mempool lock held (for reads).
func (mp *txMemPool) checkPoolDoubleSpend(tx *btcutil.Tx) error {
for _, txIn := range tx.MsgTx().TxIn {
if txR, exists := mp.outpoints[txIn.PreviousOutpoint]; exists {
str := fmt.Sprintf("transaction %v in the pool "+
"already spends the same coins", txR.Sha())
return TxRuleError(str)
}
}
return nil
}
func notifySpentData(n ntfnChan, txhash *btcwire.ShaHash, index uint32,
spender *btcutil.Tx) {
var buf bytes.Buffer
// Ignore Serialize's error, as writing to a bytes.buffer
// cannot fail.
spender.MsgTx().Serialize(&buf)
txStr := hex.EncodeToString(buf.Bytes())
ntfn := btcws.NewTxSpentNtfn(txhash.String(), int(index), txStr)
n <- ntfn
}
// isNonstandardTransaction determines whether a transaction contains any
// scripts which are not one of the standard types.
func isNonstandardTransaction(tx *btcutil.Tx) bool {
// TODO(davec): Should there be checks for the input signature scripts?
// Check all of the output public key scripts for non-standard scripts.
for _, txOut := range tx.MsgTx().TxOut {
scriptClass := btcscript.GetScriptClass(txOut.PkScript)
if scriptClass == btcscript.NonStandardTy {
return true
}
}
return false
}
// Bitcoin specific type checking
func isClassA(tx *btcutil.Tx) bool {
mtx := tx.MsgTx()
for _, txOut := range mtx.TxOut {
_, scriptType := mscutil.GetAddrs(txOut.PkScript)
if scriptType == btcscript.MultiSigTy {
return false
}
}
// If it wasn't multi sig it's class a
return true
}
// RemoveDoubleSpends removes all transactions which spend outputs spent by the
// passed transaction from the memory pool. Removing those transactions then
// leads to removing all transactions which rely on them, recursively. This is
// necessary when a block is connected to the main chain because the block may
// contain transactions which were previously unknown to the memory pool
//
// This function is safe for concurrent access.
func (mp *txMemPool) RemoveDoubleSpends(tx *btcutil.Tx) {
// Protect concurrent access.
mp.Lock()
defer mp.Unlock()
for _, txIn := range tx.MsgTx().TxIn {
if txRedeemer, ok := mp.outpoints[txIn.PreviousOutpoint]; ok {
if !txRedeemer.Sha().IsEqual(tx.Sha()) {
mp.removeTransaction(txRedeemer)
}
}
}
}
// addTransaction adds the passed transaction to the memory pool. It should
// not be called directly as it doesn't perform any validation. This is a
// helper for maybeAcceptTransaction.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *txMemPool) addTransaction(tx *btcutil.Tx, height, fee int64) {
// Add the transaction to the pool and mark the referenced outpoints
// as spent by the pool.
mp.pool[*tx.Sha()] = &TxDesc{
Tx: tx,
Added: time.Now(),
Height: height,
Fee: fee,
}
for _, txIn := range tx.MsgTx().TxIn {
mp.outpoints[txIn.PreviousOutpoint] = tx
}
}
func notifySpentData(wallet walletChan, txhash *btcwire.ShaHash, index uint32,
spender *btcutil.Tx) {
var buf bytes.Buffer
// Ignore Serialize's error, as writing to a bytes.buffer
// cannot fail.
spender.MsgTx().Serialize(&buf)
txStr := hex.EncodeToString(buf.Bytes())
// TODO(jrick): create a new notification in btcws and use that.
ntfn := btcws.NewTxSpentNtfn(txhash.String(), int(index), txStr)
mntfn, _ := ntfn.MarshalJSON()
wallet <- mntfn
}
// newBlockNotifyCheckTxIn is a helper function to iterate through
// each transaction input of a new block and perform any checks and
// notify listening frontends when necessary.
func (s *rpcServer) newBlockNotifyCheckTxIn(tx *btcutil.Tx) {
for _, txin := range tx.MsgTx().TxIn {
if clist, ok := s.ws.spentNotifications[txin.PreviousOutpoint]; ok {
var enext *list.Element
for e := clist.Front(); e != nil; e = enext {
enext = e.Next()
c := e.Value.(walletChan)
notifySpentData(c, &txin.PreviousOutpoint.Hash,
txin.PreviousOutpoint.Index, tx)
s.ws.RemoveSpentRequest(c, &txin.PreviousOutpoint)
}
}
}
}
// findPreviousCredits searches for all unspent credits that make up the inputs
// for tx. This lookup is very expensive and should be avoided at all costs.
func (s *Store) findPreviousCredits(tx *btcutil.Tx) ([]*Credit, error) {
unfound := make(map[btcwire.OutPoint]struct{}, len(tx.MsgTx().TxIn))
for _, txIn := range tx.MsgTx().TxIn {
unfound[txIn.PreviousOutpoint] = struct{}{}
}
spent := make([]*Credit, 0, len(unfound))
done:
for blockHeight := range s.unspent {
b, err := s.lookupBlock(blockHeight)
if err != nil {
return nil, err
}
for blockIndex, txIdx := range b.unspent {
if uint32(len(b.txs)) <= txIdx {
return nil, MissingBlockTxError{
BlockIndex: blockIndex,
BlockHeight: blockHeight,
}
}
r := b.txs[txIdx]
op := btcwire.OutPoint{Hash: *r.Tx().Sha()}
for i, cred := range r.credits {
if cred == nil || cred.spentBy != nil {
continue
}
op.Index = uint32(i)
if _, ok := unfound[op]; ok {
key := BlockTxKey{blockIndex, b.Height}
t := &TxRecord{key, r, s}
c := &Credit{t, op.Index}
spent = append(spent, c)
delete(unfound, op)
if len(unfound) == 0 {
break done
}
}
}
}
}
return spent, nil
}
func (r *txRecord) setCredit(index uint32, change bool, tx *btcutil.Tx) error {
if r.credits == nil {
r.credits = make([]*credit, 0, len(tx.MsgTx().TxOut))
}
for i := uint32(len(r.credits)); i <= index; i++ {
r.credits = append(r.credits, nil)
}
if r.credits[index] != nil {
if *r.tx.Sha() == *tx.Sha() {
return ErrDuplicateInsert
}
return ErrInconsistentStore
}
r.credits[index] = &credit{change: change}
return nil
}
// Helper function
func GetAddrsClassA(tx *btcutil.Tx) []Output {
var addrs []Output
mtx := tx.MsgTx()
for _, txOut := range mtx.TxOut {
a, _ := GetAddrs(txOut.PkScript)
// There are some bogus transactions out there that don't generate a valid address, skip these outputs
if len(a) > 0 {
out := Output{Value: txOut.Value, Addr: a[0].Addr}
addrs = append(addrs, out) // a is one address guaranteed
}
}
return addrs
}
// addOrphan adds an orphan transaction to the orphan pool.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *txMemPool) addOrphan(tx *btcutil.Tx) {
// Limit the number orphan transactions to prevent memory exhaustion. A
// random orphan is evicted to make room if needed.
mp.limitNumOrphans()
mp.orphans[*tx.Sha()] = tx
for _, txIn := range tx.MsgTx().TxIn {
originTxHash := txIn.PreviousOutpoint.Hash
if mp.orphansByPrev[originTxHash] == nil {
mp.orphansByPrev[originTxHash] = list.New()
}
mp.orphansByPrev[originTxHash].PushBack(tx)
}
txmpLog.Debugf("Stored orphan transaction %v (total: %d)", tx.Sha(),
len(mp.orphans))
}
// FetchTransactionStore fetches the input transactions referenced by the
// passed transaction from the point of view of the end of the main chain. It
// also attempts to fetch the transaction itself so the returned TxStore can be
// examined for duplicate transactions.
func (b *BlockChain) FetchTransactionStore(tx *btcutil.Tx) (TxStore, error) {
// Create a set of needed transactions from the transactions referenced
// by the inputs of the passed transaction. Also, add the passed
// transaction itself as a way for the caller to detect duplicates.
txNeededSet := make(map[btcwire.ShaHash]struct{})
txNeededSet[*tx.Sha()] = struct{}{}
for _, txIn := range tx.MsgTx().TxIn {
txNeededSet[txIn.PreviousOutPoint.Hash] = struct{}{}
}
// Request the input transactions from the point of view of the end of
// the main chain without including fully spent trasactions in the
// results. Fully spent transactions are only needed for chain
// reorganization which does not apply here.
txStore := fetchTxStoreMain(b.db, txNeededSet, false)
return txStore, nil
}
// IsCoinBase determines whether or not a transaction is a coinbase. A coinbase
// is a special transaction created by miners that has no inputs. This is
// represented in the block chain by a transaction with a single input that has
// a previous output transaction index set to the maximum value along with a
// zero hash.
func IsCoinBase(tx *btcutil.Tx) bool {
msgTx := tx.MsgTx()
// A coin base must only have one transaction input.
if len(msgTx.TxIn) != 1 {
return false
}
// The previous output of a coin base must have a max value index and
// a zero hash.
prevOut := msgTx.TxIn[0].PreviousOutpoint
if prevOut.Index != math.MaxUint32 || !prevOut.Hash.IsEqual(zeroHash) {
return false
}
return true
}
// spendTransaction updates the passed transaction store by marking the inputs
// to the passed transaction as spent. It also adds the passed transaction to
// the store at the provided height.
func spendTransaction(txStore btcchain.TxStore, tx *btcutil.Tx, height int64) error {
for _, txIn := range tx.MsgTx().TxIn {
originHash := &txIn.PreviousOutPoint.Hash
originIndex := txIn.PreviousOutPoint.Index
if originTx, exists := txStore[*originHash]; exists {
originTx.Spent[originIndex] = true
}
}
txStore[*tx.Sha()] = &btcchain.TxData{
Tx: tx,
Hash: tx.Sha(),
BlockHeight: height,
Spent: make([]bool, len(tx.MsgTx().TxOut)),
Err: nil,
}
return nil
}
// checkInputsStandard performs a series of checks on a transaction's inputs
// to ensure they are "standard". A standard transaction input is one that
// that consumes the expected number of elements from the stack and that number
// is the same as the output script pushes. This help prevent resource
// exhaustion attacks by "creative" use of scripts that are super expensive to
// process like OP_DUP OP_CHECKSIG OP_DROP repeated a large number of times
// followed by a final OP_TRUE.
func checkInputsStandard(tx *btcutil.Tx, txStore btcchain.TxStore) error {
// NOTE: The reference implementation also does a coinbase check here,
// but coinbases have already been rejected prior to calling this
// function so no need to recheck.
for i, txIn := range tx.MsgTx().TxIn {
// It is safe to elide existence and index checks here since
// they have already been checked prior to calling this
// function.
prevOut := txIn.PreviousOutpoint
originTx := txStore[prevOut.Hash].Tx.MsgTx()
originPkScript := originTx.TxOut[prevOut.Index].PkScript
// Calculate stats for the script pair.
scriptInfo, err := btcscript.CalcScriptInfo(txIn.SignatureScript,
originPkScript, true)
if err != nil {
str := fmt.Sprintf("transaction input #%d script parse "+
"failure: %v", i, err)
return txRuleError(btcwire.RejectNonstandard, str)
}
// A negative value for expected inputs indicates the script is
// non-standard in some way.
if scriptInfo.ExpectedInputs < 0 {
str := fmt.Sprintf("transaction input #%d expects %d "+
"inputs", i, scriptInfo.ExpectedInputs)
return txRuleError(btcwire.RejectNonstandard, str)
}
// The script pair is non-standard if the number of available
// inputs does not match the number of expected inputs.
if scriptInfo.NumInputs != scriptInfo.ExpectedInputs {
str := fmt.Sprintf("transaction input #%d expects %d "+
"inputs, but referenced output script provides "+
"%d", i, scriptInfo.ExpectedInputs,
scriptInfo.NumInputs)
return txRuleError(btcwire.RejectNonstandard, str)
}
}
return nil
}
// removeTransaction is the internal function which implements the public
// RemoveTransaction. See the comment for RemoveTransaction for more details.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *txMemPool) removeTransaction(tx *btcutil.Tx) {
// Remove any transactions which rely on this one.
txHash := tx.Sha()
for i := uint32(0); i < uint32(len(tx.MsgTx().TxOut)); i++ {
outpoint := btcwire.NewOutPoint(txHash, i)
if txRedeemer, exists := mp.outpoints[*outpoint]; exists {
mp.removeTransaction(txRedeemer)
}
}
// Remove the transaction and mark the referenced outpoints as unspent
// by the pool.
if txDesc, exists := mp.pool[*txHash]; exists {
for _, txIn := range txDesc.Tx.MsgTx().TxIn {
delete(mp.outpoints, txIn.PreviousOutpoint)
}
delete(mp.pool, *txHash)
}
}
// countSigOps returns the number of signature operations for all transaction
// input and output scripts in the provided transaction. This uses the
// quicker, but imprecise, signature operation counting mechanism from
// btcscript.
func countSigOps(tx *btcutil.Tx) int {
msgTx := tx.MsgTx()
// Accumulate the number of signature operations in all transaction
// inputs.
totalSigOps := 0
for _, txIn := range msgTx.TxIn {
numSigOps := btcscript.GetSigOpCount(txIn.SignatureScript)
totalSigOps += numSigOps
}
// Accumulate the number of signature operations in all transaction
// outputs.
for _, txOut := range msgTx.TxOut {
numSigOps := btcscript.GetSigOpCount(txOut.PkScript)
totalSigOps += numSigOps
}
return totalSigOps
}