// 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, isNew, rateLimit bool) ([]*wire.ShaHash, error) {
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 nil, txRuleError(wire.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 := blockchain.CheckTransactionSanity(tx)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, chainRuleError(cerr)
}
return 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, 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, 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 it's height is at least
// one more than the current height.
_, curHeight, err := mp.cfg.NewestSha()
if err != nil {
// This is an unexpected error so don't turn it into a rule
// error.
return nil, err
}
nextBlockHeight := curHeight + 1
// Don't allow non-standard transactions if the network parameters
// forbid their relaying.
if !activeNetParams.RelayNonStdTxs {
err := checkTransactionStandard(tx, nextBlockHeight,
mp.cfg.TimeSource, mp.cfg.MinRelayTxFee)
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, 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, 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, false)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, chainRuleError(cerr)
}
return nil, 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 nil, txRuleError(wire.RejectDuplicate,
"transaction already exists")
}
}
}
delete(txStore, *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 []*wire.ShaHash
for _, txD := range txStore {
if txD.Err == database.ErrTxShaMissing {
missingParents = append(missingParents, txD.Hash)
}
}
if len(missingParents) > 0 {
return missingParents, 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 := blockchain.CheckTransactionInputs(tx, nextBlockHeight, txStore)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, chainRuleError(cerr)
}
return nil, 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 = wire.RejectNonstandard
}
str := fmt.Sprintf("transaction %v has a non-standard "+
"input: %v", txHash, err)
return 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, txStore)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, chainRuleError(cerr)
}
return nil, err
}
numSigOps += blockchain.CountSigOps(tx)
if numSigOps > maxSigOpsPerTx {
str := fmt.Sprintf("transaction %v has too many sigops: %d > %d",
txHash, numSigOps, maxSigOpsPerTx)
return 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.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, 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.DisableRelayPriority && txFee < minFee {
currentPriority := calcPriority(tx.MsgTx(), txStore,
nextBlockHeight)
if currentPriority <= minHighPriority {
str := fmt.Sprintf("transaction %v has insufficient "+
"priority (%g <= %g)", txHash,
currentPriority, minHighPriority)
return 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()
// 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 >= mp.cfg.FreeTxRelayLimit*10*1000 {
str := fmt.Sprintf("transaction %v has been rejected "+
"by the rate limiter due to low fees", txHash)
return nil, txRuleError(wire.RejectInsufficientFee, str)
}
oldTotal := mp.pennyTotal
mp.pennyTotal += float64(serializedSize)
txmpLog.Tracef("rate limit: curTotal %v, nextTotal: %v, "+
"limit %v", oldTotal, mp.pennyTotal,
mp.cfg.FreeTxRelayLimit*10*1000)
}
// Verify crypto signatures for each input and reject the transaction if
// any don't verify.
err = blockchain.ValidateTransactionScripts(tx, txStore,
txscript.StandardVerifyFlags, mp.cfg.SigCache)
if err != nil {
if cerr, ok := err.(blockchain.RuleError); ok {
return nil, chainRuleError(cerr)
}
return nil, err
}
// Add to transaction pool.
mp.addTransaction(txStore, tx, curHeight, txFee)
txmpLog.Debugf("Accepted transaction %v (pool size: %v)", txHash,
len(mp.pool))
return nil, nil
}
// Ingest puts a tx into the DB atomically. This can result in a
// gain, a loss, or no result. Gain or loss in satoshis is returned.
func (ts *TxStore) Ingest(tx *wire.MsgTx, height int32) (uint32, error) {
var hits uint32
var err error
var spentOPs [][]byte
var nUtxoBytes [][]byte
// tx has been OK'd by SPV; check tx sanity
utilTx := btcutil.NewTx(tx) // convert for validation
// checks basic stuff like there are inputs and ouputs
err = blockchain.CheckTransactionSanity(utilTx)
if err != nil {
return hits, err
}
// note that you can't check signatures; this is SPV.
// 0 conf SPV means pretty much nothing. Anyone can say anything.
// before entering into db, serialize all inputs of the ingested tx
for _, txin := range tx.TxIn {
nOP, err := outPointToBytes(&txin.PreviousOutPoint)
if err != nil {
return hits, err
}
spentOPs = append(spentOPs, nOP)
}
// also generate PKscripts for all addresses (maybe keep storing these?)
for _, adr := range ts.Adrs {
// iterate through all our addresses
aPKscript, err := txscript.PayToAddrScript(adr.PkhAdr)
if err != nil {
return hits, err
}
// iterate through all outputs of this tx
for i, out := range tx.TxOut {
if bytes.Equal(out.PkScript, aPKscript) { // new utxo for us
var newu Utxo
newu.AtHeight = height
newu.KeyIdx = adr.KeyIdx
newu.Value = out.Value
var newop wire.OutPoint
newop.Hash = tx.TxSha()
newop.Index = uint32(i)
newu.Op = newop
b, err := newu.ToBytes()
if err != nil {
return hits, err
}
nUtxoBytes = append(nUtxoBytes, b)
hits++
break // only one match
}
}
}
err = ts.StateDB.Update(func(btx *bolt.Tx) error {
// get all 4 buckets
duf := btx.Bucket(BKTUtxos)
// sta := btx.Bucket(BKTState)
old := btx.Bucket(BKTStxos)
txns := btx.Bucket(BKTTxns)
if duf == nil || old == nil || txns == nil {
return fmt.Errorf("error: db not initialized")
}
// first see if we lose utxos
// iterate through duffel bag and look for matches
// this makes us lose money, which is regrettable, but we need to know.
for _, nOP := range spentOPs {
duf.ForEach(func(k, v []byte) error {
if bytes.Equal(k, nOP) { // matched, we lost utxo
// do all this just to figure out value we lost
x := make([]byte, len(k)+len(v))
copy(x, k)
copy(x[len(k):], v)
lostTxo, err := UtxoFromBytes(x)
if err != nil {
return err
}
hits++
// then delete the utxo from duf, save to old
err = duf.Delete(k)
if err != nil {
return err
}
// after deletion, save stxo to old bucket
var st Stxo // generate spent txo
st.Utxo = lostTxo // assign outpoint
st.SpendHeight = height // spent at height
st.SpendTxid = tx.TxSha() // spent by txid
stxb, err := st.ToBytes() // serialize
if err != nil {
return err
}
err = old.Put(k, stxb) // write k:v outpoint:stxo bytes
if err != nil {
return err
}
// store this relevant tx
sha := tx.TxSha()
var buf bytes.Buffer
tx.Serialize(&buf)
err = txns.Put(sha.Bytes(), buf.Bytes())
if err != nil {
return err
}
return nil // matched utxo k, won't match another
}
return nil // no match
})
} // done losing utxos, next gain utxos
// next add all new utxos to db, this is quick as the work is above
for _, ub := range nUtxoBytes {
err = duf.Put(ub[:36], ub[36:])
if err != nil {
return err
}
}
return nil
})
return hits, err
}