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Remove CheckMinWork, as we always know all parent headers

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This commit is contained in:
Pieter Wuille 2014-09-06 21:16:25 +02:00
parent ad6e601712
commit f244c99c96
4 changed files with 0 additions and 97 deletions
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17
src/main.cpp
View file

@ -2329,23 +2329,6 @@ bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, CBloc
return true;
}
CBlockIndex* pcheckpoint = Checkpoints::GetLastCheckpoint();
if (pcheckpoint && block.hashPrevBlock != (chainActive.Tip() ? chainActive.Tip()->GetBlockHash() : uint256(0)))
{
// Extra checks to prevent "fill up memory by spamming with bogus blocks"
int64_t deltaTime = block.GetBlockTime() - pcheckpoint->GetBlockTime();
if (deltaTime < 0)
{
return state.DoS(100, error("%s : block with timestamp before last checkpoint", __func__),
REJECT_CHECKPOINT, "time-too-old");
}
if (!CheckMinWork(block.nBits, pcheckpoint->nBits, deltaTime))
{
return state.DoS(100, error("%s : block with too little proof-of-work", __func__),
REJECT_INVALID, "bad-diffbits");
}
}
// Get prev block index
CBlockIndex* pindexPrev = NULL;
int nHeight = 0;

33
src/pow.cpp
View file

@ -98,39 +98,6 @@ bool CheckProofOfWork(uint256 hash, unsigned int nBits)
return true;
}
//
// true if nBits is greater than the minimum amount of work that could
// possibly be required deltaTime after minimum work required was nBase
//
bool CheckMinWork(unsigned int nBits, unsigned int nBase, int64_t deltaTime)
{
bool fOverflow = false;
uint256 bnNewBlock;
bnNewBlock.SetCompact(nBits, NULL, &fOverflow);
if (fOverflow)
return false;
const uint256 &bnLimit = Params().ProofOfWorkLimit();
// Testnet has min-difficulty blocks
// after Params().TargetSpacing()*2 time between blocks:
if (Params().AllowMinDifficultyBlocks() && deltaTime > Params().TargetSpacing()*2)
return bnNewBlock <= bnLimit;
uint256 bnResult;
bnResult.SetCompact(nBase);
while (deltaTime > 0 && bnResult < bnLimit)
{
// Maximum 400% adjustment...
bnResult *= 4;
// ... in best-case exactly 4-times-normal target time
deltaTime -= Params().TargetTimespan()*4;
}
if (bnResult > bnLimit)
bnResult = bnLimit;
return bnNewBlock <= bnResult;
}
void UpdateTime(CBlockHeader* pblock, const CBlockIndex* pindexPrev)
{
pblock->nTime = std::max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());

2
src/pow.h
View file

@ -16,8 +16,6 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
/** Check whether a block hash satisfies the proof-of-work requirement specified by nBits */
bool CheckProofOfWork(uint256 hash, unsigned int nBits);
/** Check the work is more than the minimum a received block needs, without knowing its direct parent */
bool CheckMinWork(unsigned int nBits, unsigned int nBase, int64_t deltaTime);
void UpdateTime(CBlockHeader* block, const CBlockIndex* pindexPrev);

45
src/test/DoS_tests.cpp
View file

@ -106,51 +106,6 @@ BOOST_AUTO_TEST_CASE(DoS_bantime)
BOOST_CHECK(!CNode::IsBanned(addr));
}
static bool CheckNBits(unsigned int nbits1, int64_t time1, unsigned int nbits2, int64_t time2)\
{
if (time1 > time2)
return CheckNBits(nbits2, time2, nbits1, time1);
int64_t deltaTime = time2-time1;
return CheckMinWork(nbits2, nbits1, deltaTime);
}
BOOST_AUTO_TEST_CASE(DoS_checknbits)
{
using namespace boost::assign; // for 'map_list_of()'
// Timestamps,nBits from the bitcoin block chain.
// These are the block-chain checkpoint blocks
typedef std::map<int64_t, unsigned int> BlockData;
BlockData chainData =
map_list_of(1239852051,486604799)(1262749024,486594666)
(1279305360,469854461)(1280200847,469830746)(1281678674,469809688)
(1296207707,453179945)(1302624061,453036989)(1309640330,437004818)
(1313172719,436789733);
// Make sure CheckNBits considers every combination of block-chain-lock-in-points
// "sane":
BOOST_FOREACH(const BlockData::value_type& i, chainData)
{
BOOST_FOREACH(const BlockData::value_type& j, chainData)
{
BOOST_CHECK(CheckNBits(i.second, i.first, j.second, j.first));
}
}
// Test a couple of insane combinations:
BlockData::value_type firstcheck = *(chainData.begin());
BlockData::value_type lastcheck = *(chainData.rbegin());
// First checkpoint difficulty at or a while after the last checkpoint time should fail when
// compared to last checkpoint
BOOST_CHECK(!CheckNBits(firstcheck.second, lastcheck.first+60*10, lastcheck.second, lastcheck.first));
BOOST_CHECK(!CheckNBits(firstcheck.second, lastcheck.first+60*60*24*14, lastcheck.second, lastcheck.first));
// ... but OK if enough time passed for difficulty to adjust downward:
BOOST_CHECK(CheckNBits(firstcheck.second, lastcheck.first+60*60*24*365*4, lastcheck.second, lastcheck.first));
}
CTransaction RandomOrphan()
{
std::map<uint256, COrphanTx>::iterator it;