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-rw-r--r--src/main.cpp7
-rw-r--r--src/pow.cpp23
-rw-r--r--src/pow.h4
-rw-r--r--src/test/DoS_tests.cpp6
4 files changed, 19 insertions, 21 deletions
diff --git a/src/main.cpp b/src/main.cpp
index fab5af73bb..9e07f43c44 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2410,12 +2410,7 @@ bool AcceptBlockHeader(CBlockHeader& block, CValidationState& state, CBlockIndex
return state.DoS(100, error("CheckBlockHeader() : block with timestamp before last checkpoint"),
REJECT_CHECKPOINT, "time-too-old");
}
- bool fOverflow = false;
- uint256 bnNewBlock;
- bnNewBlock.SetCompact(block.nBits, NULL, &fOverflow);
- uint256 bnRequired;
- bnRequired.SetCompact(ComputeMinWork(pcheckpoint->nBits, deltaTime));
- if (fOverflow || bnNewBlock > bnRequired)
+ if (!CheckMinWork(block.nBits, pcheckpoint->nBits, deltaTime))
{
return state.DoS(100, error("CheckBlockHeader() : block with too little proof-of-work"),
REJECT_INVALID, "bad-diffbits");
diff --git a/src/pow.cpp b/src/pow.cpp
index d76928bda2..1d2b743b48 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -94,29 +94,36 @@ bool CheckProofOfWork(uint256 hash, unsigned int nBits)
}
//
-// minimum amount of work that could possibly be required nTime after
-// minimum work required was nBase
+// true if nBits is greater than the minimum amount of work that could
+// possibly be required deltaTime after minimum work required was nBase
//
-unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime)
+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() && nTime > Params().TargetSpacing()*2)
- return bnLimit.GetCompact();
+ if (Params().AllowMinDifficultyBlocks() && deltaTime > Params().TargetSpacing()*2)
+ return bnNewBlock <= bnLimit;
uint256 bnResult;
bnResult.SetCompact(nBase);
- while (nTime > 0 && bnResult < bnLimit)
+ while (deltaTime > 0 && bnResult < bnLimit)
{
// Maximum 400% adjustment...
bnResult *= 4;
// ... in best-case exactly 4-times-normal target time
- nTime -= Params().TargetTimespan()*4;
+ deltaTime -= Params().TargetTimespan()*4;
}
if (bnResult > bnLimit)
bnResult = bnLimit;
- return bnResult.GetCompact();
+
+ return bnNewBlock <= bnResult;
}
void UpdateTime(CBlockHeader* pblock, const CBlockIndex* pindexPrev)
diff --git a/src/pow.h b/src/pow.h
index 6aea713fc4..f350d763f4 100644
--- a/src/pow.h
+++ b/src/pow.h
@@ -17,8 +17,8 @@ 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);
-/** Calculate the minimum amount of work a received block needs, without knowing its direct parent */
-unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime);
+/** 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);
diff --git a/src/test/DoS_tests.cpp b/src/test/DoS_tests.cpp
index 5e17555e7a..bb15db43b1 100644
--- a/src/test/DoS_tests.cpp
+++ b/src/test/DoS_tests.cpp
@@ -106,11 +106,7 @@ static bool CheckNBits(unsigned int nbits1, int64_t time1, unsigned int nbits2,
return CheckNBits(nbits2, time2, nbits1, time1);
int64_t deltaTime = time2-time1;
- uint256 required;
- required.SetCompact(ComputeMinWork(nbits1, deltaTime));
- uint256 have;
- have.SetCompact(nbits2);
- return (have <= required);
+ return CheckMinWork(nbits2, nbits1, deltaTime);
}
BOOST_AUTO_TEST_CASE(DoS_checknbits)