Exemple #1
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// 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())
	}
}
Exemple #2
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// 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,
			FeePerKB: fee * 1000 / int64(tx.MsgTx().SerializeSize()),
		},
		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
}
Exemple #3
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// 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())
	}
}
Exemple #4
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// 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()
}
Exemple #5
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// 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)
	return nil, err
}
Exemple #6
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// 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
}
Exemple #7
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// AddTxOuts adds all outputs in the passed transaction which are not provably
// unspendable to the view.  When the view already has entries for any of the
// outputs, they are simply marked unspent.  All fields will be updated for
// existing entries since it's possible it has changed during a reorg.
func (view *UtxoViewpoint) AddTxOuts(tx *btcutil.Tx, blockHeight int32) {
	// When there are not already any utxos associated with the transaction,
	// add a new entry for it to the view.
	entry := view.LookupEntry(tx.Hash())
	if entry == nil {
		entry = newUtxoEntry(tx.MsgTx().Version, IsCoinBase(tx),
			blockHeight)
		view.entries[*tx.Hash()] = entry
	} else {
		entry.blockHeight = blockHeight
	}
	entry.modified = true

	// Loop all of the transaction outputs and add those which are not
	// provably unspendable.
	for txOutIdx, txOut := range tx.MsgTx().TxOut {
		if txscript.IsUnspendable(txOut.PkScript) {
			continue
		}

		// Update existing entries.  All fields are updated because it's
		// possible (although extremely unlikely) that the existing
		// entry is being replaced by a different transaction with the
		// same hash.  This is allowed so long as the previous
		// transaction is fully spent.
		if output, ok := entry.sparseOutputs[uint32(txOutIdx)]; ok {
			output.spent = false
			output.compressed = false
			output.amount = txOut.Value
			output.pkScript = txOut.PkScript
			continue
		}

		// Add the unspent transaction output.
		entry.sparseOutputs[uint32(txOutIdx)] = &utxoOutput{
			spent:      false,
			compressed: false,
			amount:     txOut.Value,
			pkScript:   txOut.PkScript,
		}
	}
	return
}
Exemple #8
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// 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()
	}
}
Exemple #9
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// 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))
}
Exemple #10
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// ValidateTransactionScripts validates the scripts for the passed transaction
// using multiple goroutines.
func ValidateTransactionScripts(tx *btcutil.Tx, utxoView *UtxoViewpoint,
	flags txscript.ScriptFlags, sigCache *txscript.SigCache,
	hashCache *txscript.HashCache) error {

	// If the hashcache doesn't yet has the sighash midstate for this
	// transaction, then we'll compute them now so we can re-use them
	// amongst all worker validation goroutines.
	if !hashCache.ContainsHashes(tx.Hash()) {
		hashCache.AddSigHashes(tx.MsgTx())
	}

	// The same pointer to the transaction's sighash midstate will be
	// re-used amongst all validation goroutines. By pre-computing the
	// sighash here instead of during validation, we ensure the sighashes
	// are only computed once.
	cachedHashes, _ := hashCache.GetSigHashes(tx.Hash())

	// 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,
			sigHashes: cachedHashes,
		}
		txValItems = append(txValItems, txVI)
	}

	// Validate all of the inputs.
	validator := newTxValidator(utxoView, flags, sigCache, hashCache)
	return validator.Validate(txValItems)
}
Exemple #11
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// FetchUtxoView loads utxo details about 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 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 (b *BlockChain) FetchUtxoView(tx *btcutil.Tx) (*UtxoViewpoint, error) {
	b.chainLock.RLock()
	defer b.chainLock.RUnlock()

	// Create a set of needed transactions based on those referenced by the
	// inputs of the passed transaction.  Also, add the passed transaction
	// itself as a way for the caller to detect duplicates that are not
	// fully spent.
	txNeededSet := make(map[chainhash.Hash]struct{})
	txNeededSet[*tx.Hash()] = struct{}{}
	if !IsCoinBase(tx) {
		for _, txIn := range tx.MsgTx().TxIn {
			txNeededSet[txIn.PreviousOutPoint.Hash] = struct{}{}
		}
	}

	// Request the utxos from the point of view of the end of the main
	// chain.
	view := NewUtxoViewpoint()
	err := view.fetchUtxosMain(b.db, txNeededSet)
	return view, err
}
Exemple #12
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// GetSigOpCost returns the unified sig op cost for the passed transaction
// respecting current active soft-forks which modified sig op cost counting.
// The unified sig op cost for a transaction is computed as the sum of: the
// legacy sig op count scaled according to the WitnessScaleFactor, the sig op
// count for all p2sh inputs scaled by the WitnessScaleFactor, and finally the
// unscaled sig op count for any inputs spending witness programs.
func GetSigOpCost(tx *btcutil.Tx, isCoinBaseTx bool, utxoView *UtxoViewpoint,
	bip16, segWit bool) (int, error) {

	numSigOps := CountSigOps(tx) * WitnessScaleFactor
	if bip16 {
		numP2SHSigOps, err := CountP2SHSigOps(tx, isCoinBaseTx, utxoView)
		if err != nil {
			return 0, nil
		}
		numSigOps += (numP2SHSigOps * WitnessScaleFactor)
	}

	if segWit && !isCoinBaseTx {
		msgTx := tx.MsgTx()
		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)
			}

			witness := txIn.Witness
			sigScript := txIn.SignatureScript
			pkScript := txEntry.PkScriptByIndex(originTxIndex)

			numSigOps += txscript.GetWitnessSigOpCount(sigScript, pkScript, witness)
		}

	}

	return numSigOps, nil
}
Exemple #13
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// 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)
}
Exemple #14
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// 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.
	// TODO(roasbeef): last bool should be conditional on segwit activation
	sigOpCost, err := blockchain.GetSigOpCost(tx, false, utxoView, true, true)
	if err != nil {
		if cerr, ok := err.(blockchain.RuleError); ok {
			return nil, nil, chainRuleError(cerr)
		}
		return nil, nil, err
	}
	if sigOpCost > mp.cfg.Policy.MaxSigOpCostPerTx {
		str := fmt.Sprintf("transaction %v sigop cost is too high: %d > %d",
			txHash, sigOpCost, maxStandardSigOpsCost)
		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 := blockchain.GetTxVirtualSize(tx)
	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,
		mp.cfg.HashCache)
	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
}
Exemple #15
0
// 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 := 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
}