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fix(consensus): require multiplicity-correct MN payment matching after v24 #7377

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Merged
PastaPastaPasta merged 2 commits into from
Jul 8, 2026
Merged

fix(consensus): require multiplicity-correct MN payment matching after v24 #7377

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84a6ba1
fix(consensus): require multiplicity-correct MN payment matching afte…
thepastaclaw Jul 7, 2026
0a40716
test: cover the v24 MN payment multiplicity boundary end-to-end
UdjinM6 Jul 8, 2026
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1 change: 1 addition & 0 deletions src/Makefile.test.include
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Original file line number Diff line number Diff line change
Expand Up @@ -142,6 +142,7 @@ BITCOIN_TESTS =\
test/llmq_snapshot_tests.cpp \
test/llmq_utils_tests.cpp \
test/logging_tests.cpp \
test/masternode_payments_tests.cpp \
test/dbwrapper_tests.cpp \
test/validation_tests.cpp \
test/mempool_tests.cpp \
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63 changes: 48 additions & 15 deletions src/masternode/payments.cpp
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Expand Up @@ -21,6 +21,36 @@
#include <ranges>
#include <string>

int FindUnmatchedMasternodePayment(const std::vector<CTxOut>& expected,
const std::vector<CTxOut>& actual,
bool strict_multiplicity)
{
if (!strict_multiplicity) {
for (size_t i = 0; i < expected.size(); ++i) {
const auto& txout = expected[i];
if (!std::ranges::any_of(actual, [&txout](const auto& txout2) { return txout == txout2; })) {
return static_cast<int>(i);
}
}
return -1;
}

std::vector<bool> consumed(actual.size(), false);
for (size_t i = 0; i < expected.size(); ++i) {
const auto& txout = expected[i];
bool found = false;
for (size_t j = 0; j < actual.size(); ++j) {
if (!consumed[j] && actual[j] == txout) {
consumed[j] = true;
found = true;
break;
}
}
if (!found) return static_cast<int>(i);
}
return -1;
}

CAmount PlatformShare(const CAmount reward)
{
const CAmount platformReward = reward * 375 / 1000;
Expand Down Expand Up @@ -184,7 +214,7 @@ CAmount GetMasternodePayment(int nHeight, CAmount blockValue, const Consensus::P
}

[[nodiscard]] bool CMNPaymentsProcessor::IsTransactionValid(const CTransaction& txNew, const CBlockIndex* pindexPrev, const CAmount blockSubsidy,
const CAmount feeReward, MnRewardEra era)
const CAmount feeReward, MnRewardEra era, bool strict_multiplicity)
{
const int nBlockHeight = pindexPrev == nullptr ? 0 : pindexPrev->nHeight + 1;
if (!DeploymentDIP0003Enforced(nBlockHeight, m_consensus_params)) {
Expand All @@ -198,19 +228,22 @@ CAmount GetMasternodePayment(int nHeight, CAmount blockValue, const Consensus::P
return true;
}

for (const auto& txout : voutMasternodePayments) {
bool found = std::ranges::any_of(txNew.vout, [&txout](const auto& txout2) { return txout == txout2; });
if (!found) {
std::string str_payout;
if (CTxDestination dest; ExtractDestination(txout.scriptPubKey, dest)) {
str_payout = "address=" + EncodeDestination(dest);
} else {
str_payout = "scriptPubKey=" + HexStr(txout.scriptPubKey);
}
LogPrintf("CMNPaymentsProcessor::%s -- ERROR! Failed to find expected payee %s amount=%lld height=%d\n",
__func__, str_payout, txout.nValue, nBlockHeight);
return false;
// With strict multiplicity (v24 active, computed by the caller) each expected payment must be
// matched by a distinct coinbase output: duplicate expected outputs require duplicate coinbase
// outputs. Pre-v24 retains the legacy existence-only check to avoid tightening historical
// validation.
const int unmatched_idx = FindUnmatchedMasternodePayment(voutMasternodePayments, txNew.vout, strict_multiplicity);
if (unmatched_idx >= 0) {
const auto& txout = voutMasternodePayments[unmatched_idx];
std::string str_payout;
if (CTxDestination dest; ExtractDestination(txout.scriptPubKey, dest)) {
str_payout = "address=" + EncodeDestination(dest);
} else {
str_payout = "scriptPubKey=" + HexStr(txout.scriptPubKey);
}
LogPrintf("CMNPaymentsProcessor::%s -- ERROR! Failed to find expected payee %s amount=%lld height=%d\n",
__func__, str_payout, txout.nValue, nBlockHeight);
return false;
}
return true;
}
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thepastaclaw marked this conversation as resolved.
Expand Down Expand Up @@ -339,12 +372,12 @@ bool CMNPaymentsProcessor::IsBlockValueValid(const CChain& active_chain, const C
return true;
}

bool CMNPaymentsProcessor::IsBlockPayeeValid(const CChain& active_chain, const CTransaction& txNew, const CBlockIndex* pindexPrev, const CAmount blockSubsidy, const CAmount feeReward, MnRewardEra era, SuperBlockCheckType check_superblock)
bool CMNPaymentsProcessor::IsBlockPayeeValid(const CChain& active_chain, const CTransaction& txNew, const CBlockIndex* pindexPrev, const CAmount blockSubsidy, const CAmount feeReward, MnRewardEra era, bool strict_multiplicity, SuperBlockCheckType check_superblock)
{
const int nBlockHeight = pindexPrev == nullptr ? 0 : pindexPrev->nHeight + 1;

// Check for correct masternode payment
if (IsTransactionValid(txNew, pindexPrev, blockSubsidy, feeReward, era)) {
if (IsTransactionValid(txNew, pindexPrev, blockSubsidy, feeReward, era, strict_multiplicity)) {

@knst knst Jul 7, 2026 •
edited
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consider changing strict_multiplicity == true to check_superblock == SuperBlockCheckType::DisallowDuplicates for CMNPaymentsProcessor::IsBlockPayeeValid to reduce amount of arguments.

They are semantically the same meaning.

@thepastaclaw thepastaclaw Jul 8, 2026

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I think we need to keep these separate. check_superblock == DisallowDuplicates also encodes whether superblock validation is being run at all: NoCheck is used for chainlocked blocks / during sync, even when v24 is active. IsBlockPayeeValid() still validates the masternode payee before the later NoCheck return, so deriving strict multiplicity from check_superblock would disable the new v24 masternode-payment multiplicity rule in those skip-superblock cases. The extra bool is a little noisier, but it preserves the deployment-state distinction from the superblock-check mode.

LogPrint(BCLog::MNPAYMENTS, "CMNPaymentsProcessor::%s -- Valid masternode payment at height %d: %s", __func__, nBlockHeight, txNew.ToString()); /* Continued */
} else {
LogPrintf("CMNPaymentsProcessor::%s -- ERROR! Invalid masternode payment detected at height %d: %s", __func__, nBlockHeight, txNew.ToString()); /* Continued */
Expand Down
23 changes: 21 additions & 2 deletions src/masternode/payments.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,25 @@ class CDeterministicMNManager;
class CTransaction;
class CTxOut;

/**
* Match the list of expected masternode payment outputs against the coinbase
* outputs.
*
* When @p strict_multiplicity is true, every expected output must be matched
* by a distinct actual output (multiplicity-correct matching): two identical
* expected outputs require two identical actual outputs.
*
* When false, the legacy behaviour is used where each expected output only
* has to appear at least once in the actual outputs. This is preserved for
* pre-v24 historical validation.
*
* @return -1 if every expected output is matched, otherwise the index in
* @p expected of the first output that could not be matched.
*/
int FindUnmatchedMasternodePayment(const std::vector<CTxOut>& expected,
const std::vector<CTxOut>& actual,
bool strict_multiplicity);

struct CMutableTransaction;

namespace governance {
Expand Down Expand Up @@ -65,7 +84,7 @@ class CMNPaymentsProcessor
[[nodiscard]] bool GetMasternodeTxOuts(const CBlockIndex* pindexPrev, const CAmount blockSubsidy, const CAmount feeReward,
MnRewardEra era, std::vector<CTxOut>& voutMasternodePaymentsRet);
[[nodiscard]] bool IsTransactionValid(const CTransaction& txNew, const CBlockIndex* pindexPrev, const CAmount blockSubsidy,
const CAmount feeReward, MnRewardEra era);
const CAmount feeReward, MnRewardEra era, bool strict_multiplicity);
[[nodiscard]] bool IsOldBudgetBlockValueValid(const CBlock& block, const int nBlockHeight, const CAmount blockReward, std::string& strErrorRet);

public:
Expand All @@ -78,7 +97,7 @@ class CMNPaymentsProcessor
}

bool IsBlockValueValid(const CChain& active_chain, const CBlock& block, const CBlockIndex* pindexPrev, const CAmount blockReward, std::string& strErrorRet, SuperBlockCheckType check_superblock);
bool IsBlockPayeeValid(const CChain& active_chain, const CTransaction& txNew, const CBlockIndex* pindexPrev, const CAmount blockSubsidy, const CAmount feeReward, MnRewardEra era, SuperBlockCheckType check_superblock);
bool IsBlockPayeeValid(const CChain& active_chain, const CTransaction& txNew, const CBlockIndex* pindexPrev, const CAmount blockSubsidy, const CAmount feeReward, MnRewardEra era, bool strict_multiplicity, SuperBlockCheckType check_superblock);
void FillBlockPayments(CMutableTransaction& txNew, const CBlockIndex* pindexPrev, const CAmount blockSubsidy, const CAmount feeReward,
MnRewardEra era, std::vector<CTxOut>& voutMasternodePaymentsRet, std::vector<CTxOut>& voutSuperblockPaymentsRet);
};
Expand Down
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