// 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 *TxPool) addTransaction(utxoView *blockchain.UtxoViewpoint, tx *btcutil.Tx, height int32, fee int64) *TxDesc {
// Add the transaction to the pool and mark the referenced outpoints
// as spent by the pool.
txD := &TxDesc{
TxDesc: mining.TxDesc{
Tx: tx,
Added: time.Now(),
Height: height,
Fee: fee,
},
StartingPriority: mining.CalcPriority(tx.MsgTx(), utxoView, height),
}
mp.pool[*tx.Hash()] = txD
for _, txIn := range tx.MsgTx().TxIn {
mp.outpoints[txIn.PreviousOutPoint] = tx
}
atomic.StoreInt64(&mp.lastUpdated, time.Now().Unix())
// Add unconfirmed address index entries associated with the transaction
// if enabled.
if mp.cfg.AddrIndex != nil {
mp.cfg.AddrIndex.AddUnconfirmedTx(tx, utxoView)
}
return txD
}
// 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 *TxPool) removeTransaction(tx *btcutil.Tx, removeRedeemers bool) {
txHash := tx.Hash()
if removeRedeemers {
// Remove any transactions which rely on this one.
for i := uint32(0); i < uint32(len(tx.MsgTx().TxOut)); i++ {
prevOut := wire.OutPoint{Hash: *txHash, Index: i}
if txRedeemer, exists := mp.outpoints[prevOut]; exists {
mp.removeTransaction(txRedeemer, true)
}
}
}
// Remove the transaction if needed.
if txDesc, exists := mp.pool[*txHash]; exists {
// Remove unconfirmed address index entries associated with the
// transaction if enabled.
if mp.cfg.AddrIndex != nil {
mp.cfg.AddrIndex.RemoveUnconfirmedTx(txHash)
}
// Mark the referenced outpoints as unspent by the pool.
for _, txIn := range txDesc.Tx.MsgTx().TxIn {
delete(mp.outpoints, txIn.PreviousOutPoint)
}
delete(mp.pool, *txHash)
atomic.StoreInt64(&mp.lastUpdated, time.Now().Unix())
}
}
// 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.Hash()[:])
// 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 := txscript.PushedData(txOut.PkScript)
if err != nil {
continue
}
for _, data := range pushedData {
if !bf.matches(data) {
continue
}
matched = true
bf.maybeAddOutpoint(txOut.PkScript, tx.Hash(), 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 := txscript.PushedData(txin.SignatureScript)
if err != nil {
continue
}
for _, data := range pushedData {
if bf.matches(data) {
return true
}
}
}
return false
}
// ProcessTransaction is the main workhorse for handling insertion of new
// free-standing transactions into the memory pool. It includes functionality
// such as rejecting duplicate transactions, ensuring transactions follow all
// rules, orphan transaction handling, and insertion into the memory pool.
//
// It returns a slice of transactions added to the mempool. When the
// error is nil, the list will include the passed transaction itself along
// with any additional orphan transaactions that were added as a result of
// the passed one being accepted.
//
// This function is safe for concurrent access.
func (mp *TxPool) ProcessTransaction(tx *btcutil.Tx, allowOrphan, rateLimit bool, tag Tag) ([]*TxDesc, error) {
log.Tracef("Processing transaction %v", tx.Hash())
// Protect concurrent access.
mp.mtx.Lock()
defer mp.mtx.Unlock()
// Potentially accept the transaction to the memory pool.
missingParents, txD, err := mp.maybeAcceptTransaction(tx, true, rateLimit,
true)
if err != nil {
return nil, err
}
if len(missingParents) == 0 {
// Accept any orphan transactions that depend on this
// transaction (they may no longer be orphans if all inputs
// are now available) and repeat for those accepted
// transactions until there are no more.
newTxs := mp.processOrphans(tx)
acceptedTxs := make([]*TxDesc, len(newTxs)+1)
// Add the parent transaction first so remote nodes
// do not add orphans.
acceptedTxs[0] = txD
copy(acceptedTxs[1:], newTxs)
return acceptedTxs, nil
}
// The transaction is an orphan (has inputs missing). Reject
// it if the flag to allow orphans is not set.
if !allowOrphan {
// Only use the first missing parent transaction in
// the error message.
//
// NOTE: RejectDuplicate is really not an accurate
// reject code here, but it matches the reference
// implementation and there isn't a better choice due
// to the limited number of reject codes. Missing
// inputs is assumed to mean they are already spent
// which is not really always the case.
str := fmt.Sprintf("orphan transaction %v references "+
"outputs of unknown or fully-spent "+
"transaction %v", tx.Hash(), missingParents[0])
return nil, txRuleError(wire.RejectDuplicate, str)
}
// Potentially add the orphan transaction to the orphan pool.
err = mp.maybeAddOrphan(tx, tag)
if err != nil {
return nil, err
}
return nil, nil
}
// logSkippedDeps logs any dependencies which are also skipped as a result of
// skipping a transaction while generating a block template at the trace level.
func logSkippedDeps(tx *btcutil.Tx, deps map[chainhash.Hash]*txPrioItem) {
if deps == nil {
return
}
for _, item := range deps {
log.Tracef("Skipping tx %s since it depends on %s\n",
item.tx.Hash(), tx.Hash())
}
}
// logSkippedDeps logs any dependencies which are also skipped as a result of
// skipping a transaction while generating a block template at the trace level.
func logSkippedDeps(tx *btcutil.Tx, deps *list.List) {
if deps == nil {
return
}
for e := deps.Front(); e != nil; e = e.Next() {
item := e.Value.(*txPrioItem)
minrLog.Tracef("Skipping tx %s since it depends on %s\n",
item.tx.Hash(), tx.Hash())
}
}
// 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 *TxPool) RemoveDoubleSpends(tx *btcutil.Tx) {
// Protect concurrent access.
mp.mtx.Lock()
for _, txIn := range tx.MsgTx().TxIn {
if txRedeemer, ok := mp.outpoints[txIn.PreviousOutPoint]; ok {
if !txRedeemer.Hash().IsEqual(tx.Hash()) {
mp.removeTransaction(txRedeemer, true)
}
}
}
mp.mtx.Unlock()
}
// 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 the script engine which
// requires access to the input transaction scripts.
func CountP2SHSigOps(tx *btcutil.Tx, isCoinBaseTx bool, utxoView *UtxoViewpoint) (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 txInIndex, txIn := range msgTx.TxIn {
// Ensure the referenced input transaction is available.
originTxHash := &txIn.PreviousOutPoint.Hash
originTxIndex := txIn.PreviousOutPoint.Index
txEntry := utxoView.LookupEntry(originTxHash)
if txEntry == nil || txEntry.IsOutputSpent(originTxIndex) {
str := fmt.Sprintf("unable to find unspent output "+
"%v referenced from transaction %s:%d",
txIn.PreviousOutPoint, tx.Hash(), txInIndex)
return 0, ruleError(ErrMissingTx, str)
}
// We're only interested in pay-to-script-hash types, so skip
// this input if it's not one.
pkScript := txEntry.PkScriptByIndex(originTxIndex)
if !txscript.IsPayToScriptHash(pkScript) {
continue
}
// Count the precise number of signature operations in the
// referenced public key script.
sigScript := txIn.SignatureScript
numSigOps := txscript.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 "+
"%v contains too many signature operations - "+
"overflow", txIn.PreviousOutPoint)
return 0, ruleError(ErrTooManySigOps, str)
}
}
return totalSigOps, nil
}
// FetchUtxoView loads utxo details about the input transactions referenced by
// the passed transaction from the point of view of the fake chain.
// It also attempts to fetch the utxo details for the transaction itself so the
// returned view can be examined for duplicate unspent transaction outputs.
//
// This function is safe for concurrent access however the returned view is NOT.
func (s *fakeChain) FetchUtxoView(tx *btcutil.Tx) (*blockchain.UtxoViewpoint, error) {
s.RLock()
defer s.RUnlock()
// All entries are cloned to ensure modifications to the returned view
// do not affect the fake chain's view.
// Add an entry for the tx itself to the new view.
viewpoint := blockchain.NewUtxoViewpoint()
entry := s.utxos.LookupEntry(tx.Hash())
viewpoint.Entries()[*tx.Hash()] = entry.Clone()
// Add entries for all of the inputs to the tx to the new view.
for _, txIn := range tx.MsgTx().TxIn {
originHash := &txIn.PreviousOutPoint.Hash
entry := s.utxos.LookupEntry(originHash)
viewpoint.Entries()[*originHash] = entry.Clone()
}
return viewpoint, nil
}
// addOrphan adds an orphan transaction to the orphan pool.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *TxPool) addOrphan(tx *btcutil.Tx, tag Tag) {
// Nothing to do if no orphans are allowed.
if mp.cfg.Policy.MaxOrphanTxs <= 0 {
return
}
// Limit the number orphan transactions to prevent memory exhaustion.
// This will periodically remove any expired orphans and evict a random
// orphan if space is still needed.
mp.limitNumOrphans()
mp.orphans[*tx.Hash()] = &orphanTx{
tx: tx,
tag: tag,
expiration: time.Now().Add(orphanTTL),
}
for _, txIn := range tx.MsgTx().TxIn {
if _, exists := mp.orphansByPrev[txIn.PreviousOutPoint]; !exists {
mp.orphansByPrev[txIn.PreviousOutPoint] =
make(map[chainhash.Hash]*btcutil.Tx)
}
mp.orphansByPrev[txIn.PreviousOutPoint][*tx.Hash()] = tx
}
log.Debugf("Stored orphan transaction %v (total: %d)", tx.Hash(),
len(mp.orphans))
}
// indexUnconfirmedAddresses modifies the unconfirmed (memory-only) address
// index to include mappings for the addresses encoded by the passed public key
// script to the transaction.
//
// This function is safe for concurrent access.
func (idx *AddrIndex) indexUnconfirmedAddresses(pkScript []byte, tx *btcutil.Tx) {
// The error is ignored here since the only reason it can fail is if the
// script fails to parse and it was already validated before being
// admitted to the mempool.
_, addresses, _, _ := txscript.ExtractPkScriptAddrs(pkScript,
idx.chainParams)
for _, addr := range addresses {
// Ignore unsupported address types.
addrKey, err := addrToKey(addr)
if err != nil {
continue
}
// Add a mapping from the address to the transaction.
idx.unconfirmedLock.Lock()
addrIndexEntry := idx.txnsByAddr[addrKey]
if addrIndexEntry == nil {
addrIndexEntry = make(map[chainhash.Hash]*btcutil.Tx)
idx.txnsByAddr[addrKey] = addrIndexEntry
}
addrIndexEntry[*tx.Hash()] = tx
// Add a mapping from the transaction to the address.
addrsByTxEntry := idx.addrsByTx[*tx.Hash()]
if addrsByTxEntry == nil {
addrsByTxEntry = make(map[[addrKeySize]byte]struct{})
idx.addrsByTx[*tx.Hash()] = addrsByTxEntry
}
addrsByTxEntry[addrKey] = struct{}{}
idx.unconfirmedLock.Unlock()
}
}
// removeOrphan is the internal function which implements the public
// RemoveOrphan. See the comment for RemoveOrphan for more details.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *TxPool) removeOrphan(tx *btcutil.Tx, removeRedeemers bool) {
// Nothing to do if passed tx is not an orphan.
txHash := tx.Hash()
otx, exists := mp.orphans[*txHash]
if !exists {
return
}
// Remove the reference from the previous orphan index.
for _, txIn := range otx.tx.MsgTx().TxIn {
orphans, exists := mp.orphansByPrev[txIn.PreviousOutPoint]
if exists {
delete(orphans, *txHash)
// Remove the map entry altogether if there are no
// longer any orphans which depend on it.
if len(orphans) == 0 {
delete(mp.orphansByPrev, txIn.PreviousOutPoint)
}
}
}
// Remove any orphans that redeem outputs from this one if requested.
if removeRedeemers {
prevOut := wire.OutPoint{Hash: *txHash}
for txOutIdx := range tx.MsgTx().TxOut {
prevOut.Index = uint32(txOutIdx)
for _, orphan := range mp.orphansByPrev[prevOut] {
mp.removeOrphan(orphan, true)
}
}
}
// Remove the transaction from the orphan pool.
delete(mp.orphans, *txHash)
}
// testPoolMembership tests the transaction pool associated with the provided
// test context to determine if the passed transaction matches the provided
// orphan pool and transaction pool status. It also further determines if it
// should be reported as available by the HaveTransaction function based upon
// the two flags and tests that condition as well.
func testPoolMembership(tc *testContext, tx *btcutil.Tx, inOrphanPool, inTxPool bool) {
txHash := tx.Hash()
gotOrphanPool := tc.harness.txPool.IsOrphanInPool(txHash)
if inOrphanPool != gotOrphanPool {
_, file, line, _ := runtime.Caller(1)
tc.t.Fatalf("%s:%d -- IsOrphanInPool: want %v, got %v", file,
line, inOrphanPool, gotOrphanPool)
}
gotTxPool := tc.harness.txPool.IsTransactionInPool(txHash)
if inTxPool != gotTxPool {
_, file, line, _ := runtime.Caller(1)
tc.t.Fatalf("%s:%d -- IsTransactionInPool: want %v, got %v",
file, line, inTxPool, gotTxPool)
}
gotHaveTx := tc.harness.txPool.HaveTransaction(txHash)
wantHaveTx := inOrphanPool || inTxPool
if wantHaveTx != gotHaveTx {
_, file, line, _ := runtime.Caller(1)
tc.t.Fatalf("%s:%d -- HaveTransaction: want %v, got %v", file,
line, wantHaveTx, gotHaveTx)
}
}
// addOrphan adds an orphan transaction to the orphan pool.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *TxPool) 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.Hash()] = tx
for _, txIn := range tx.MsgTx().TxIn {
originTxHash := txIn.PreviousOutPoint.Hash
if _, exists := mp.orphansByPrev[originTxHash]; !exists {
mp.orphansByPrev[originTxHash] =
make(map[chainhash.Hash]*btcutil.Tx)
}
mp.orphansByPrev[originTxHash][*tx.Hash()] = tx
}
log.Debugf("Stored orphan transaction %v (total: %d)", tx.Hash(),
len(mp.orphans))
}
// maybeAcceptTransaction is the internal function which implements the public
// MaybeAcceptTransaction. See the comment for MaybeAcceptTransaction for
// more details.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *TxPool) maybeAcceptTransaction(tx *btcutil.Tx, isNew, rateLimit, rejectDupOrphans bool) ([]*chainhash.Hash, *TxDesc, error) {
txHash := tx.Hash()
// Don't accept the transaction if it already exists in the pool. This
// applies to orphan transactions as well when the reject duplicate
// orphans flag is set. This check is intended to be a quick check to
// weed out duplicates.
if mp.isTransactionInPool(txHash) || (rejectDupOrphans &&
mp.isOrphanInPool(txHash)) {
str := fmt.Sprintf("already have transaction %v", txHash)
return nil, nil, txRuleError(wire.RejectDuplicate, str)
}
// Perform preliminary sanity checks on the transaction. This makes
// use of blockchain which contains the invariant rules for what
// transactions are allowed into blocks.
err := blockchain.CheckTransactionSanity(tx)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, nil, chainRuleError(cerr)
}
return nil, nil, err
}
// A standalone transaction must not be a coinbase transaction.
if blockchain.IsCoinBase(tx) {
str := fmt.Sprintf("transaction %v is an individual coinbase",
txHash)
return nil, nil, txRuleError(wire.RejectInvalid, str)
}
// Don't accept transactions with a lock time after the maximum int32
// value for now. This is an artifact of older bitcoind clients which
// treated this field as an int32 and would treat anything larger
// incorrectly (as negative).
if tx.MsgTx().LockTime > math.MaxInt32 {
str := fmt.Sprintf("transaction %v has a lock time after "+
"2038 which is not accepted yet", txHash)
return nil, nil, txRuleError(wire.RejectNonstandard, str)
}
// Get the current height of the main chain. A standalone transaction
// will be mined into the next block at best, so its height is at least
// one more than the current height.
bestHeight := mp.cfg.BestHeight()
nextBlockHeight := bestHeight + 1
medianTimePast := mp.cfg.MedianTimePast()
// Don't allow non-standard transactions if the network parameters
// forbid their acceptance.
if !mp.cfg.Policy.AcceptNonStd {
err = checkTransactionStandard(tx, nextBlockHeight,
medianTimePast, mp.cfg.Policy.MinRelayTxFee,
mp.cfg.Policy.MaxTxVersion)
if err != nil {
// Attempt to extract a reject code from the error so
// it can be retained. When not possible, fall back to
// a non standard error.
rejectCode, found := extractRejectCode(err)
if !found {
rejectCode = wire.RejectNonstandard
}
str := fmt.Sprintf("transaction %v is not standard: %v",
txHash, err)
return nil, nil, txRuleError(rejectCode, str)
}
}
// The transaction may not use any of the same outputs as other
// transactions already in the pool as that would ultimately result in a
// double spend. This check is intended to be quick and therefore only
// detects double spends within the transaction pool itself. The
// transaction could still be double spending coins from the main chain
// at this point. There is a more in-depth check that happens later
// after fetching the referenced transaction inputs from the main chain
// which examines the actual spend data and prevents double spends.
err = mp.checkPoolDoubleSpend(tx)
if err != nil {
return nil, nil, err
}
// Fetch all of the unspent transaction outputs referenced by the inputs
// to this transaction. This function also attempts to fetch the
// transaction itself to be used for detecting a duplicate transaction
// without needing to do a separate lookup.
utxoView, err := mp.fetchInputUtxos(tx)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, nil, chainRuleError(cerr)
}
return nil, nil, err
}
// Don't allow the transaction if it exists in the main chain and is not
// not already fully spent.
txEntry := utxoView.LookupEntry(txHash)
if txEntry != nil && !txEntry.IsFullySpent() {
return nil, nil, txRuleError(wire.RejectDuplicate,
"transaction already exists")
}
delete(utxoView.Entries(), *txHash)
// Transaction is an orphan if any of the referenced input transactions
// don't exist. Adding orphans to the orphan pool is not handled by
// this function, and the caller should use maybeAddOrphan if this
// behavior is desired.
var missingParents []*chainhash.Hash
for originHash, entry := range utxoView.Entries() {
if entry == nil || entry.IsFullySpent() {
// Must make a copy of the hash here since the iterator
// is replaced and taking its address directly would
// result in all of the entries pointing to the same
// memory location and thus all be the final hash.
hashCopy := originHash
missingParents = append(missingParents, &hashCopy)
}
}
if len(missingParents) > 0 {
return missingParents, nil, nil
}
// Don't allow the transaction into the mempool unless its sequence
// lock is active, meaning that it'll be allowed into the next block
// with respect to its defined relative lock times.
sequenceLock, err := mp.cfg.CalcSequenceLock(tx, utxoView)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, nil, chainRuleError(cerr)
}
return nil, nil, err
}
if !blockchain.SequenceLockActive(sequenceLock, nextBlockHeight,
medianTimePast) {
return nil, nil, txRuleError(wire.RejectNonstandard,
"transaction's sequence locks on inputs not met")
}
// Perform several checks on the transaction inputs using the invariant
// rules in blockchain for what transactions are allowed into blocks.
// Also returns the fees associated with the transaction which will be
// used later.
txFee, err := blockchain.CheckTransactionInputs(tx, nextBlockHeight,
utxoView, mp.cfg.ChainParams)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, nil, chainRuleError(cerr)
}
return nil, nil, err
}
// Don't allow transactions with non-standard inputs if the network
// parameters forbid their acceptance.
if !mp.cfg.Policy.AcceptNonStd {
err := checkInputsStandard(tx, utxoView)
if err != nil {
// Attempt to extract a reject code from the error so
// it can be retained. When not possible, fall back to
// a non standard error.
rejectCode, found := extractRejectCode(err)
if !found {
rejectCode = wire.RejectNonstandard
}
str := fmt.Sprintf("transaction %v has a non-standard "+
"input: %v", txHash, err)
return nil, nil, txRuleError(rejectCode, str)
}
}
// NOTE: if you modify this code to accept non-standard transactions,
// you should add code here to check that the transaction does a
// reasonable number of ECDSA signature verifications.
// Don't allow transactions with an excessive number of signature
// operations which would result in making it impossible to mine. Since
// the coinbase address itself can contain signature operations, the
// maximum allowed signature operations per transaction is less than
// the maximum allowed signature operations per block.
numSigOps, err := blockchain.CountP2SHSigOps(tx, false, utxoView)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, nil, chainRuleError(cerr)
}
return nil, nil, err
}
numSigOps += blockchain.CountSigOps(tx)
if numSigOps > mp.cfg.Policy.MaxSigOpsPerTx {
str := fmt.Sprintf("transaction %v has too many sigops: %d > %d",
txHash, numSigOps, mp.cfg.Policy.MaxSigOpsPerTx)
return nil, nil, txRuleError(wire.RejectNonstandard, str)
}
// Don't allow transactions with fees too low to get into a mined block.
//
// 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.
serializedSize := int64(tx.MsgTx().SerializeSize())
minFee := calcMinRequiredTxRelayFee(serializedSize,
mp.cfg.Policy.MinRelayTxFee)
if serializedSize >= (DefaultBlockPrioritySize-1000) && txFee < minFee {
str := fmt.Sprintf("transaction %v has %d fees which is under "+
"the required amount of %d", txHash, txFee,
minFee)
return nil, nil, txRuleError(wire.RejectInsufficientFee, str)
}
// Require that free transactions have sufficient priority to be mined
// in the next block. Transactions which are being added back to the
// memory pool from blocks that have been disconnected during a reorg
// are exempted.
if isNew && !mp.cfg.Policy.DisableRelayPriority && txFee < minFee {
currentPriority := mining.CalcPriority(tx.MsgTx(), utxoView,
nextBlockHeight)
if currentPriority <= mining.MinHighPriority {
str := fmt.Sprintf("transaction %v has insufficient "+
"priority (%g <= %g)", txHash,
currentPriority, mining.MinHighPriority)
return nil, nil, txRuleError(wire.RejectInsufficientFee, str)
}
}
// Free-to-relay transactions are rate limited here to prevent
// penny-flooding with tiny transactions as a form of attack.
if rateLimit && txFee < minFee {
nowUnix := time.Now().Unix()
// Decay passed data with an exponentially decaying ~10 minute
// window - matches bitcoind handling.
mp.pennyTotal *= math.Pow(1.0-1.0/600.0,
float64(nowUnix-mp.lastPennyUnix))
mp.lastPennyUnix = nowUnix
// Are we still over the limit?
if mp.pennyTotal >= mp.cfg.Policy.FreeTxRelayLimit*10*1000 {
str := fmt.Sprintf("transaction %v has been rejected "+
"by the rate limiter due to low fees", txHash)
return nil, nil, txRuleError(wire.RejectInsufficientFee, str)
}
oldTotal := mp.pennyTotal
mp.pennyTotal += float64(serializedSize)
log.Tracef("rate limit: curTotal %v, nextTotal: %v, "+
"limit %v", oldTotal, mp.pennyTotal,
mp.cfg.Policy.FreeTxRelayLimit*10*1000)
}
// Verify crypto signatures for each input and reject the transaction if
// any don't verify.
err = blockchain.ValidateTransactionScripts(tx, utxoView,
txscript.StandardVerifyFlags, mp.cfg.SigCache)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, nil, chainRuleError(cerr)
}
return nil, nil, err
}
// Add to transaction pool.
txD := mp.addTransaction(utxoView, tx, bestHeight, txFee)
log.Debugf("Accepted transaction %v (pool size: %v)", txHash,
len(mp.pool))
return nil, txD, nil
}
// CheckTransactionInputs performs a series of checks on the inputs to a
// transaction to ensure they are valid. An example of some of the checks
// include verifying all inputs exist, ensuring the coinbase seasoning
// requirements are met, detecting double spends, validating all values and fees
// are in the legal range and the total output amount doesn't exceed the input
// amount, and verifying the signatures to prove the spender was the owner of
// the bitcoins and therefore allowed to spend them. As it checks the inputs,
// it also calculates the total fees for the transaction and returns that value.
//
// NOTE: The transaction MUST have already been sanity checked with the
// CheckTransactionSanity function prior to calling this function.
func CheckTransactionInputs(tx *btcutil.Tx, txHeight int32, utxoView *UtxoViewpoint, chainParams *chaincfg.Params) (int64, error) {
// Coinbase transactions have no inputs.
if IsCoinBase(tx) {
return 0, nil
}
txHash := tx.Hash()
var totalSatoshiIn int64
for txInIndex, txIn := range tx.MsgTx().TxIn {
// Ensure the referenced input transaction is available.
originTxHash := &txIn.PreviousOutPoint.Hash
utxoEntry := utxoView.LookupEntry(originTxHash)
if utxoEntry == nil {
str := fmt.Sprintf("unable to find unspent output "+
"%v referenced from transaction %s:%d",
txIn.PreviousOutPoint, tx.Hash(), txInIndex)
return 0, ruleError(ErrMissingTx, str)
}
// Ensure the transaction is not spending coins which have not
// yet reached the required coinbase maturity.
if utxoEntry.IsCoinBase() {
originHeight := int32(utxoEntry.BlockHeight())
blocksSincePrev := txHeight - originHeight
coinbaseMaturity := int32(chainParams.CoinbaseMaturity)
if blocksSincePrev < coinbaseMaturity {
str := fmt.Sprintf("tried to spend coinbase "+
"transaction %v from height %v at "+
"height %v before required maturity "+
"of %v blocks", originTxHash,
originHeight, txHeight,
coinbaseMaturity)
return 0, ruleError(ErrImmatureSpend, str)
}
}
// Ensure the transaction is not double spending coins.
originTxIndex := txIn.PreviousOutPoint.Index
if utxoEntry.IsOutputSpent(originTxIndex) {
str := fmt.Sprintf("transaction %s:%d tried to double "+
"spend output %v", txHash, txInIndex,
txIn.PreviousOutPoint)
return 0, ruleError(ErrDoubleSpend, str)
}
// Ensure the transaction amounts are in range. Each of the
// output values of the input transactions must not be negative
// or more than the max allowed per transaction. All amounts in
// a transaction are in a unit value known as a satoshi. One
// bitcoin is a quantity of satoshi as defined by the
// SatoshiPerBitcoin constant.
originTxSatoshi := utxoEntry.AmountByIndex(originTxIndex)
if originTxSatoshi < 0 {
str := fmt.Sprintf("transaction output has negative "+
"value of %v", btcutil.Amount(originTxSatoshi))
return 0, ruleError(ErrBadTxOutValue, str)
}
if originTxSatoshi > btcutil.MaxSatoshi {
str := fmt.Sprintf("transaction output value of %v is "+
"higher than max allowed value of %v",
btcutil.Amount(originTxSatoshi),
btcutil.MaxSatoshi)
return 0, ruleError(ErrBadTxOutValue, str)
}
// The total of all outputs must not be more than the max
// allowed per transaction. Also, we could potentially overflow
// the accumulator so check for overflow.
lastSatoshiIn := totalSatoshiIn
totalSatoshiIn += originTxSatoshi
if totalSatoshiIn < lastSatoshiIn ||
totalSatoshiIn > btcutil.MaxSatoshi {
str := fmt.Sprintf("total value of all transaction "+
"inputs is %v which is higher than max "+
"allowed value of %v", totalSatoshiIn,
btcutil.MaxSatoshi)
return 0, ruleError(ErrBadTxOutValue, str)
}
}
// Calculate the total output amount for this transaction. It is safe
// to ignore overflow and out of range errors here because those error
// conditions would have already been caught by checkTransactionSanity.
var totalSatoshiOut int64
for _, txOut := range tx.MsgTx().TxOut {
totalSatoshiOut += txOut.Value
}
// Ensure the transaction does not spend more than its inputs.
if totalSatoshiIn < totalSatoshiOut {
str := fmt.Sprintf("total value of all transaction inputs for "+
"transaction %v is %v which is less than the amount "+
"spent of %v", txHash, totalSatoshiIn, totalSatoshiOut)
return 0, ruleError(ErrSpendTooHigh, str)
}
// NOTE: bitcoind checks if the transaction fees are < 0 here, but that
// is an impossible condition because of the check above that ensures
// the inputs are >= the outputs.
txFeeInSatoshi := totalSatoshiIn - totalSatoshiOut
return txFeeInSatoshi, nil
}
// txOutToSpendableOut returns a spendable output given a transaction and index
// of the output to use. This is useful as a convenience when creating test
// transactions.
func txOutToSpendableOut(tx *btcutil.Tx, outputNum uint32) spendableOutput {
return spendableOutput{
outPoint: wire.OutPoint{Hash: *tx.Hash(), Index: outputNum},
amount: btcutil.Amount(tx.MsgTx().TxOut[outputNum].Value),
}
}