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Detect any sufficiently long fork and add a warning.

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.
tags/v0.15.1
Matt Corallo 8 years ago
parent
commit
b8585384da
1 changed files with 56 additions and 5 deletions
  1. 56
    5
      src/main.cpp

+ 56
- 5
src/main.cpp View File

@@ -1383,6 +1383,56 @@ bool IsInitialBlockDownload()
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)
{
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",
hashBestChain.ToString().c_str(), nBestHeight, log(nBestChainWork.getdouble())/log(2.0),
DateTimeStrFormat("%Y-%m-%d %H:%M:%S", pindexBest->GetBlockTime()).c_str());
if (pindexBest && nBestInvalidWork > nBestChainWork + (pindexBest->GetBlockWork() * 6).getuint256())
printf("InvalidChainFound: Warning: Displayed transactions may not be correct! You may need to upgrade, or other nodes may need to upgrade.\n");
CheckForkWarningConditions();
}

void static InvalidBlockFound(CBlockIndex *pindex) {
@@ -2110,11 +2159,14 @@ bool AddToBlockIndex(CBlock& block, CValidationState& state, const CDiskBlockPos

if (pindexNew == pindexBest)
{
// Clear fork warning if its no longer applicable
CheckForkWarningConditions();
// Notify UI to display prev block's coinbase if it was ours
static uint256 hashPrevBestCoinBase;
UpdatedTransaction(hashPrevBestCoinBase);
hashPrevBestCoinBase = block.GetTxHash(0);
}
} else
CheckForkWarningConditionsOnNewFork(pindexNew);

if (!pblocktree->Flush())
return state.Abort(_("Failed to sync block index"));
@@ -3073,8 +3125,7 @@ string GetWarnings(string strFor)
strStatusBar = strMiscWarning;
}

// Longer invalid proof-of-work chain
if (pindexBest && nBestInvalidWork > nBestChainWork + (pindexBest->GetBlockWork() * 6).getuint256())
if (fLargeWorkForkFound)
{
nPriority = 2000;
strStatusBar = strRPC = _("Warning: Displayed transactions may not be correct! You may need to upgrade, or other nodes may need to upgrade.");

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