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MOVEONLY: check that fees > direct conflicts to policy/rbf

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This commit is contained in:
glozow 2021-08-11 15:51:27 +01:00
parent 3f033f01a6
commit 9c2f9f8984
3 changed files with 43 additions and 24 deletions
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32
src/policy/rbf.cpp
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@ -129,3 +129,35 @@ std::optional<std::string> EntriesAndTxidsDisjoint(const CTxMemPool::setEntries&
}
return std::nullopt;
}
std::optional<std::string> PaysMoreThanConflicts(const CTxMemPool::setEntries& setIterConflicting,
CFeeRate newFeeRate,
const uint256& hash)
{
for (const auto& mi : setIterConflicting) {
// Don't allow the replacement to reduce the feerate of the
// mempool.
//
// We usually don't want to accept replacements with lower
// feerates than what they replaced as that would lower the
// feerate of the next block. Requiring that the feerate always
// be increased is also an easy-to-reason about way to prevent
// DoS attacks via replacements.
//
// We only consider the feerates of transactions being directly
// replaced, not their indirect descendants. While that does
// mean high feerate children are ignored when deciding whether
// or not to replace, we do require the replacement to pay more
// overall fees too, mitigating most cases.
CFeeRate oldFeeRate(mi->GetModifiedFee(), mi->GetTxSize());
if (newFeeRate <= oldFeeRate)
{
return strprintf("rejecting replacement %s; new feerate %s <= old feerate %s",
hash.ToString(),
newFeeRate.ToString(),
oldFeeRate.ToString());
}
}
return std::nullopt;
}

9
src/policy/rbf.h
View file

@ -69,4 +69,13 @@ std::optional<std::string> HasNoNewUnconfirmed(const CTransaction& tx, const CTx
std::optional<std::string> EntriesAndTxidsDisjoint(const CTxMemPool::setEntries& setAncestors,
const std::set<uint256>& setConflicts,
const uint256& txid);
/** Check that the feerate of the replacement transaction(s) is higher than the feerate of each
* of the transactions in setIterConflicting.
* @param[in] setIterConflicting The set of mempool entries.
* @returns error message if fees insufficient, otherwise std::nullopt.
*/
std::optional<std::string> PaysMoreThanConflicts(const CTxMemPool::setEntries& setIterConflicting,
CFeeRate newFeeRate, const uint256& hash);
#endif // BITCOIN_POLICY_RBF_H

26
src/validation.cpp
View file

@ -782,30 +782,8 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
if (fReplacementTransaction)
{
CFeeRate newFeeRate(nModifiedFees, nSize);
for (const auto& mi : setIterConflicting) {
// Don't allow the replacement to reduce the feerate of the
// mempool.
//
// We usually don't want to accept replacements with lower
// feerates than what they replaced as that would lower the
// feerate of the next block. Requiring that the feerate always
// be increased is also an easy-to-reason about way to prevent
// DoS attacks via replacements.
//
// We only consider the feerates of transactions being directly
// replaced, not their indirect descendants. While that does
// mean high feerate children are ignored when deciding whether
// or not to replace, we do require the replacement to pay more
// overall fees too, mitigating most cases.
CFeeRate oldFeeRate(mi->GetModifiedFee(), mi->GetTxSize());
if (newFeeRate <= oldFeeRate)
{
return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "insufficient fee",
strprintf("rejecting replacement %s; new feerate %s <= old feerate %s",
hash.ToString(),
newFeeRate.ToString(),
oldFeeRate.ToString()));
}
if (const auto err_string{PaysMoreThanConflicts(setIterConflicting, newFeeRate, hash)}) {
return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "insufficient fee", *err_string);
}
// Calculate all conflicting entries and enforce Rule #5.