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refactor: add GetMinimumTime() helper

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Before bip94 there was an assumption that the minimum permitted
timestamp is GetMedianTimePast() + 1.

This commit splits a helper function out of UpdateTime() to
obtain the minimum time in a way that takes the
timewarp attack rule into account.
This commit is contained in:
Sjors Provoost 2025-01-03 15:23:39 +01:00
parent b432e36742
commit 0713548137
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GPG key ID: 57FF9BDBCC301009
2 changed files with 23 additions and 7 deletions
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23
src/node/miner.cpp
View file

@ -28,16 +28,25 @@
#include <utility>
namespace node {
int64_t GetMinimumTime(const CBlockIndex* pindexPrev, const int64_t difficulty_adjustment_interval)
{
int64_t min_time{pindexPrev->GetMedianTimePast() + 1};
// Height of block to be mined.
const int height{pindexPrev->nHeight + 1};
// Account for BIP94 timewarp rule on all networks. This makes future
// activation safer.
if (height % difficulty_adjustment_interval == 0) {
min_time = std::max<int64_t>(min_time, pindexPrev->GetBlockTime() - MAX_TIMEWARP);
}
return min_time;
}
int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev)
{
int64_t nOldTime = pblock->nTime;
int64_t nNewTime{std::max<int64_t>(pindexPrev->GetMedianTimePast() + 1, TicksSinceEpoch<std::chrono::seconds>(NodeClock::now()))};
// Height of block to be mined.
const int height{pindexPrev->nHeight + 1};
if (height % consensusParams.DifficultyAdjustmentInterval() == 0) {
nNewTime = std::max<int64_t>(nNewTime, pindexPrev->GetBlockTime() - MAX_TIMEWARP);
}
int64_t nNewTime{std::max<int64_t>(GetMinimumTime(pindexPrev, consensusParams.DifficultyAdjustmentInterval()),
TicksSinceEpoch<std::chrono::seconds>(NodeClock::now()))};
if (nOldTime < nNewTime) {
pblock->nTime = nNewTime;

7
src/node/miner.h
View file

@ -211,6 +211,13 @@ private:
void SortForBlock(const CTxMemPool::setEntries& package, std::vector<CTxMemPool::txiter>& sortedEntries);
};
/**
* Get the minimum time a miner should use in the next block. This always
* accounts for the BIP94 timewarp rule, so does not necessarily reflect the
* consensus limit.
*/
int64_t GetMinimumTime(const CBlockIndex* pindexPrev, const int64_t difficulty_adjustment_interval);
int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev);
/** Update an old GenerateCoinbaseCommitment from CreateNewBlock after the block txs have changed */