Exemplo n.º 1
0
// maybeAcceptTransaction is the main workhorse for handling insertion of new
// free-standing transactions into a memory pool.  It includes functionality
// such as rejecting duplicate transactions, ensuring transactions follow all
// rules, orphan transaction handling, and insertion into the memory pool.
func (mp *txMemPool) maybeAcceptTransaction(tx *btcwire.MsgTx, isOrphan *bool) error {
	*isOrphan = false
	txHash, err := tx.TxSha()
	if err != nil {
		return err
	}

	// Don't accept the transaction if it already exists in the pool.  This
	// applies to orphan transactions as well.  This check is intended to
	// be a quick check to weed out duplicates.  It is more expensive to
	// detect a duplicate transaction in the main chain, so that is done
	// later.
	if mp.isTransactionInPool(&txHash) {
		str := fmt.Sprintf("already have transaction %v", txHash)
		return TxRuleError(str)
	}

	// Perform preliminary sanity checks on the transaction.  This makes
	// use of btcchain which contains the invariant rules for what
	// transactions are allowed into blocks.
	err = btcchain.CheckTransactionSanity(tx)
	if err != nil {
		if _, ok := err.(btcchain.RuleError); ok {
			return TxRuleError(err.Error())
		}
		return err
	}

	// A standalone transaction must not be a coinbase transaction.
	if btcchain.IsCoinBase(tx) {
		str := fmt.Sprintf("transaction %v is an individual coinbase",
			txHash)
		return TxRuleError(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.LockTime > math.MaxInt32 {
		str := fmt.Sprintf("transaction %v is has a lock time after "+
			"2038 which is not accepted yet", txHash)
		return TxRuleError(str)
	}

	// Get the current height of the main chain.  A standalone transaction
	// will be mined into the next block at best, so
	_, curHeight, err := mp.server.db.NewestSha()
	if err != nil {
		return err
	}
	nextBlockHeight := curHeight + 1

	// Don't allow non-standard transactions on the main network.
	if activeNetParams.btcnet == btcwire.MainNet {
		err := checkTransactionStandard(tx, nextBlockHeight)
		if err != nil {
			str := fmt.Sprintf("transaction %v is not a standard "+
				"transaction: %v", txHash, err)
			return TxRuleError(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 err
	}

	// Fetch all of the transactions 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.
	txStore, err := mp.fetchInputTransactions(tx)
	if err != nil {
		return err
	}

	// Don't allow the transaction if it exists in the main chain and is not
	// not already fully spent.
	if txD, exists := txStore[txHash]; exists && txD.Err == nil {
		for _, isOutputSpent := range txD.Spent {
			if !isOutputSpent {
				str := fmt.Sprintf("transaction already exists")
				return TxRuleError(str)
			}
		}
	}
	delete(txStore, txHash)

	// Transaction is an orphan if any of the inputs don't exist.
	for _, txD := range txStore {
		if txD.Err == btcdb.TxShaMissing {
			*isOrphan = true
			return nil
		}
	}

	// Perform several checks on the transaction inputs using the invariant
	// rules in btcchain for what transactions are allowed into blocks.
	// Also returns the fees associated with the transaction which will be
	// used later.
	txFee, err := btcchain.CheckTransactionInputs(tx, nextBlockHeight, txStore)
	if err != nil {
		return err
	}

	// Don't allow transactions with non-standard inputs on the main
	// network.
	if activeNetParams.btcnet == btcwire.MainNet {
		err := checkInputsStandard(tx)
		if err != nil {
			str := fmt.Sprintf("transaction %v has a non-standard "+
				"input: %v", txHash, err)
			return TxRuleError(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.

	// TODO(davec): Don't allow the transaction if the transation fee
	// would be too low to get into an empty block.
	_ = txFee

	// Verify crypto signatures for each input and reject the transaction if
	// any don't verify.
	err = btcchain.ValidateTransactionScripts(tx, &txHash, time.Now(), txStore)
	if err != nil {
		return err
	}

	// TODO(davec): Rate-limit free transactions

	// Add to transaction pool.
	mp.addTransaction(tx, &txHash)

	mp.lock.RLock()
	log.Debugf("[TXMP] Accepted transaction %v (pool size: %v)", txHash,
		len(mp.pool))
	mp.lock.RUnlock()

	// TODO(davec): Notifications

	// Generate the inventory vector and relay it.
	iv := btcwire.NewInvVect(btcwire.InvVect_Tx, &txHash)
	mp.server.RelayInventory(iv)

	return nil
}
Exemplo n.º 2
0
// 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 *txMemPool) maybeAcceptTransaction(tx *btcutil.Tx, isOrphan *bool, isNew, rateLimit bool) error {
	if isOrphan != nil {
		*isOrphan = false
	}
	txHash := tx.Sha()

	// Don't accept the transaction if it already exists in the pool.  This
	// applies to orphan transactions as well.  This check is intended to
	// be a quick check to weed out duplicates.
	if mp.haveTransaction(txHash) {
		str := fmt.Sprintf("already have transaction %v", txHash)
		return TxRuleError(str)
	}

	// Perform preliminary sanity checks on the transaction.  This makes
	// use of btcchain which contains the invariant rules for what
	// transactions are allowed into blocks.
	err := btcchain.CheckTransactionSanity(tx)
	if err != nil {
		if _, ok := err.(btcchain.RuleError); ok {
			return TxRuleError(err.Error())
		}
		return err
	}

	// A standalone transaction must not be a coinbase transaction.
	if btcchain.IsCoinBase(tx) {
		str := fmt.Sprintf("transaction %v is an individual coinbase",
			txHash)
		return TxRuleError(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 TxRuleError(str)
	}

	// Get the current height of the main chain.  A standalone transaction
	// will be mined into the next block at best, so it's height is at least
	// one more than the current height.
	_, curHeight, err := mp.server.db.NewestSha()
	if err != nil {
		return err
	}
	nextBlockHeight := curHeight + 1

	// Don't allow non-standard transactions if the network parameters
	// forbid their relaying.
	if !activeNetParams.RelayNonStdTxs {
		err := checkTransactionStandard(tx, nextBlockHeight)
		if err != nil {
			str := fmt.Sprintf("transaction %v is not a standard "+
				"transaction: %v", txHash, err)
			return TxRuleError(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 err
	}

	// Fetch all of the transactions 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.
	txStore, err := mp.fetchInputTransactions(tx)
	if err != nil {
		return err
	}

	// Don't allow the transaction if it exists in the main chain and is not
	// not already fully spent.
	if txD, exists := txStore[*txHash]; exists && txD.Err == nil {
		for _, isOutputSpent := range txD.Spent {
			if !isOutputSpent {
				return TxRuleError("transaction already exists")
			}
		}
	}
	delete(txStore, *txHash)

	// Transaction is an orphan if any of the inputs don't exist.
	for _, txD := range txStore {
		if txD.Err == btcdb.TxShaMissing {
			if isOrphan != nil {
				*isOrphan = true
			}
			return nil
		}
	}

	// Perform several checks on the transaction inputs using the invariant
	// rules in btcchain for what transactions are allowed into blocks.
	// Also returns the fees associated with the transaction which will be
	// used later.
	txFee, err := btcchain.CheckTransactionInputs(tx, nextBlockHeight, txStore)
	if err != nil {
		if _, ok := err.(btcchain.RuleError); ok {
			return TxRuleError(err.Error())
		}
		return err
	}

	// Don't allow transactions with non-standard inputs if the network
	// parameters forbid their relaying.
	if !activeNetParams.RelayNonStdTxs {
		err := checkInputsStandard(tx, txStore)
		if err != nil {
			str := fmt.Sprintf("transaction %v has a non-standard "+
				"input: %v", txHash, err)
			return TxRuleError(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 fees too low to get into a mined block.
	minRequiredFee := calcMinRelayFee(tx)
	if txFee < minRequiredFee {
		str := fmt.Sprintf("transaction %v has %d fees which is under "+
			"the required amount of %d", txHash, txFee,
			minRequiredFee)
		return TxRuleError(str)
	}

	// Free-to-relay transactions are rate limited here to prevent
	// penny-flooding with tiny transactions as a form of attack.
	if rateLimit && minRequiredFee == 0 {
		nowUnix := time.Now().Unix()
		// we decay passed data with an exponentially decaying ~10
		// minutes 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 >= cfg.FreeTxRelayLimit*10*1000 {
			str := fmt.Sprintf("transaction %v has 0 fees and has "+
				"been rejected by the rate limiter", txHash)
			return TxRuleError(str)
		}
		oldTotal := mp.pennyTotal

		mp.pennyTotal += float64(tx.MsgTx().SerializeSize())
		txmpLog.Tracef("rate limit: curTotal %v, nextTotal: %v, "+
			"limit %v", oldTotal, mp.pennyTotal,
			cfg.FreeTxRelayLimit*10*1000)
	}

	// Verify crypto signatures for each input and reject the transaction if
	// any don't verify.
	err = btcchain.ValidateTransactionScripts(tx, txStore,
		standardScriptVerifyFlags)
	if err != nil {
		return err
	}

	// Add to transaction pool.
	mp.addTransaction(tx, curHeight, txFee)

	txmpLog.Debugf("Accepted transaction %v (pool size: %v)", txHash,
		len(mp.pool))

	// Notify websocket clients about mempool transactions.
	if mp.server.rpcServer != nil {
		mp.server.rpcServer.ntfnMgr.NotifyMempoolTx(tx, isNew)
	}

	return nil
}
Exemplo n.º 3
0
// 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 *txMemPool) maybeAcceptTransaction(tx *btcutil.Tx, isOrphan *bool, isNew, rateLimit bool) error {
	if isOrphan != nil {
		*isOrphan = false
	}
	txHash := tx.Sha()

	// Don't accept the transaction if it already exists in the pool.  This
	// applies to orphan transactions as well.  This check is intended to
	// be a quick check to weed out duplicates.
	if mp.haveTransaction(txHash) {
		str := fmt.Sprintf("already have transaction %v", txHash)
		return txRuleError(btcwire.RejectDuplicate, str)
	}

	// Perform preliminary sanity checks on the transaction.  This makes
	// use of btcchain which contains the invariant rules for what
	// transactions are allowed into blocks.
	err := btcchain.CheckTransactionSanity(tx)
	if err != nil {
		if cerr, ok := err.(btcchain.RuleError); ok {
			return chainRuleError(cerr)
		}
		return err
	}

	// A standalone transaction must not be a coinbase transaction.
	if btcchain.IsCoinBase(tx) {
		str := fmt.Sprintf("transaction %v is an individual coinbase",
			txHash)
		return txRuleError(btcwire.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 txRuleError(btcwire.RejectNonstandard, str)
	}

	// Get the current height of the main chain.  A standalone transaction
	// will be mined into the next block at best, so it's height is at least
	// one more than the current height.
	_, curHeight, err := mp.server.db.NewestSha()
	if err != nil {
		// This is an unexpected error so don't turn it into a rule
		// error.
		return err
	}
	nextBlockHeight := curHeight + 1

	// Don't allow non-standard transactions if the network parameters
	// forbid their relaying.
	if !activeNetParams.RelayNonStdTxs {
		err := checkTransactionStandard(tx, nextBlockHeight)
		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 = btcwire.RejectNonstandard
			}
			str := fmt.Sprintf("transaction %v is not standard: %v",
				txHash, err)
			return 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 err
	}

	// Fetch all of the transactions 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.
	txStore, err := mp.fetchInputTransactions(tx)
	if err != nil {
		if cerr, ok := err.(btcchain.RuleError); ok {
			return chainRuleError(cerr)
		}
		return err
	}

	// Don't allow the transaction if it exists in the main chain and is not
	// not already fully spent.
	if txD, exists := txStore[*txHash]; exists && txD.Err == nil {
		for _, isOutputSpent := range txD.Spent {
			if !isOutputSpent {
				return txRuleError(btcwire.RejectDuplicate,
					"transaction already exists")
			}
		}
	}
	delete(txStore, *txHash)

	// Transaction is an orphan if any of the inputs don't exist.
	for _, txD := range txStore {
		if txD.Err == btcdb.ErrTxShaMissing {
			if isOrphan != nil {
				*isOrphan = true
			}
			return nil
		}
	}

	// Perform several checks on the transaction inputs using the invariant
	// rules in btcchain for what transactions are allowed into blocks.
	// Also returns the fees associated with the transaction which will be
	// used later.
	txFee, err := btcchain.CheckTransactionInputs(tx, nextBlockHeight, txStore)
	if err != nil {
		if cerr, ok := err.(btcchain.RuleError); ok {
			return chainRuleError(cerr)
		}
		return err
	}

	// Don't allow transactions with non-standard inputs if the network
	// parameters forbid their relaying.
	if !activeNetParams.RelayNonStdTxs {
		err := checkInputsStandard(tx, txStore)
		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 = btcwire.RejectNonstandard
			}
			str := fmt.Sprintf("transaction %v has a non-standard "+
				"input: %v", txHash, err)
			return 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 := btcchain.CountP2SHSigOps(tx, false, txStore)
	if err != nil {
		if cerr, ok := err.(btcchain.RuleError); ok {
			return chainRuleError(cerr)
		}
		return err
	}
	numSigOps += btcchain.CountSigOps(tx)
	if numSigOps > maxSigOpsPerTx {
		str := fmt.Sprintf("transaction %v has too many sigops: %d > %d",
			txHash, numSigOps, maxSigOpsPerTx)
		return txRuleError(btcwire.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)
	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 txRuleError(btcwire.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()
		// we decay passed data with an exponentially decaying ~10
		// minutes 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 >= cfg.FreeTxRelayLimit*10*1000 {
			str := fmt.Sprintf("transaction %v has been rejected "+
				"by the rate limiter due to low fees", txHash)
			return txRuleError(btcwire.RejectInsufficientFee, str)
		}
		oldTotal := mp.pennyTotal

		mp.pennyTotal += float64(serializedSize)
		txmpLog.Tracef("rate limit: curTotal %v, nextTotal: %v, "+
			"limit %v", oldTotal, mp.pennyTotal,
			cfg.FreeTxRelayLimit*10*1000)
	}

	// Verify crypto signatures for each input and reject the transaction if
	// any don't verify.
	err = btcchain.ValidateTransactionScripts(tx, txStore,
		standardScriptVerifyFlags)
	if err != nil {
		if cerr, ok := err.(btcchain.RuleError); ok {
			return chainRuleError(cerr)
		}
		return err
	}

	// Add to transaction pool.
	mp.addTransaction(tx, curHeight, txFee)

	txmpLog.Debugf("Accepted transaction %v (pool size: %v)", txHash,
		len(mp.pool))

	if mp.server.rpcServer != nil {
		// Notify websocket clients about mempool transactions.
		mp.server.rpcServer.ntfnMgr.NotifyMempoolTx(tx, isNew)

		// Potentially notify any getblocktemplate long poll clients
		// about stale block templates due to the new transaction.
		mp.server.rpcServer.gbtWorkState.NotifyMempoolTx(mp.lastUpdated)
	}

	return nil
}