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Detect any sufficiently long fork and add a warning.

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Such a fork is defined as being at least 7 blocks long and
having a tip which is within 72 blocks of our best block.
This commit is contained in:
Matt Corallo 2013-05-07 18:33:52 +02:00
parent 4eab2dcc81
commit b8585384da
1 changed files with 56 additions and 5 deletions
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61
src/main.cpp
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@ -1383,6 +1383,56 @@ bool IsInitialBlockDownload()
pindexBest->GetBlockTime() < GetTime() - 24 * 60 * 60); pindexBest->GetBlockTime() < GetTime() - 24 * 60 * 60);
} }
bool fLargeWorkForkFound = false;
CBlockIndex *pindexBestForkTip = NULL, *pindexBestForkBase = NULL;
void CheckForkWarningConditions()
{
// If our best fork is no longer within 72 blocks (+/- 12 hours if no one mines it)
// of our head, drop it
if (pindexBestForkTip && nBestHeight - pindexBestForkTip->nHeight >= 72)
pindexBestForkTip = NULL;
if (pindexBestForkTip || nBestInvalidWork > nBestChainWork + (pindexBest->GetBlockWork() * 6).getuint256())
{
fLargeWorkForkFound = true;
printf("CheckForkWarningConditions: Warning: Displayed transactions may not be correct! You may need to upgrade, or other nodes may need to upgrade.\n");
} else
fLargeWorkForkFound = false;
}
void CheckForkWarningConditionsOnNewFork(CBlockIndex* pindexNewForkTip)
{
// If we are on a fork that is sufficiently large, set a warning flag
CBlockIndex* pfork = pindexNewForkTip;
CBlockIndex* plonger = pindexBest;
while (pfork && pfork != plonger)
{
while (plonger && plonger->nHeight > pfork->nHeight)
plonger = plonger->pprev;
if (pfork == plonger)
break;
pfork = pfork->pprev;
}
// We define a condition which we should warn the user about as a fork of at least 7 blocks
// who's tip is within 72 blocks (+/- 12 hours if no one mines it) of ours
// We use 7 blocks rather arbitrarily as it represents just under 10% of sustained network
// hash rate operating on the fork.
// or a chain that is entirely longer than ours and invalid (note that this should be detected by both)
// We define it this way because it allows us to only store the highest fork tip (+ base) which meets
// the 7-block condition and from this always have the most-likely-to-cause-warning fork
if (pfork && (!pindexBestForkTip || (pindexBestForkTip && pindexNewForkTip->nHeight > pindexBestForkTip->nHeight)) &&
pindexNewForkTip->nChainWork - pfork->nChainWork > (pfork->GetBlockWork() * 7).getuint256() &&
nBestHeight - pindexNewForkTip->nHeight < 72)
{
pindexBestForkTip = pindexNewForkTip;
pindexBestForkBase = pfork;
}
CheckForkWarningConditions();
}
void static InvalidChainFound(CBlockIndex* pindexNew) void static InvalidChainFound(CBlockIndex* pindexNew)
{ {
if (pindexNew->nChainWork > nBestInvalidWork) if (pindexNew->nChainWork > nBestInvalidWork)
@ -1398,8 +1448,7 @@ void static InvalidChainFound(CBlockIndex* pindexNew)
printf("InvalidChainFound: current best=%s height=%d log2_work=%.8g date=%s\n", printf("InvalidChainFound: current best=%s height=%d log2_work=%.8g date=%s\n",
hashBestChain.ToString().c_str(), nBestHeight, log(nBestChainWork.getdouble())/log(2.0), hashBestChain.ToString().c_str(), nBestHeight, log(nBestChainWork.getdouble())/log(2.0),
DateTimeStrFormat("%Y-%m-%d %H:%M:%S", pindexBest->GetBlockTime()).c_str()); DateTimeStrFormat("%Y-%m-%d %H:%M:%S", pindexBest->GetBlockTime()).c_str());
if (pindexBest && nBestInvalidWork > nBestChainWork + (pindexBest->GetBlockWork() * 6).getuint256()) CheckForkWarningConditions();
printf("InvalidChainFound: Warning: Displayed transactions may not be correct! You may need to upgrade, or other nodes may need to upgrade.\n");
} }
void static InvalidBlockFound(CBlockIndex *pindex) { void static InvalidBlockFound(CBlockIndex *pindex) {
@ -2110,11 +2159,14 @@ bool AddToBlockIndex(CBlock& block, CValidationState& state, const CDiskBlockPos
if (pindexNew == pindexBest) if (pindexNew == pindexBest)
{ {
// Clear fork warning if its no longer applicable
CheckForkWarningConditions();
// Notify UI to display prev block's coinbase if it was ours // Notify UI to display prev block's coinbase if it was ours
static uint256 hashPrevBestCoinBase; static uint256 hashPrevBestCoinBase;
UpdatedTransaction(hashPrevBestCoinBase); UpdatedTransaction(hashPrevBestCoinBase);
hashPrevBestCoinBase = block.GetTxHash(0); hashPrevBestCoinBase = block.GetTxHash(0);
} } else
CheckForkWarningConditionsOnNewFork(pindexNew);
if (!pblocktree->Flush()) if (!pblocktree->Flush())
return state.Abort(_("Failed to sync block index")); return state.Abort(_("Failed to sync block index"));
@ -3073,8 +3125,7 @@ string GetWarnings(string strFor)
strStatusBar = strMiscWarning; strStatusBar = strMiscWarning;
} }
// Longer invalid proof-of-work chain if (fLargeWorkForkFound)
if (pindexBest && nBestInvalidWork > nBestChainWork + (pindexBest->GetBlockWork() * 6).getuint256())
{ {
nPriority = 2000; nPriority = 2000;
strStatusBar = strRPC = _("Warning: Displayed transactions may not be correct! You may need to upgrade, or other nodes may need to upgrade."); strStatusBar = strRPC = _("Warning: Displayed transactions may not be correct! You may need to upgrade, or other nodes may need to upgrade.");