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Merge pull request #5947

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36cba8f Alert if it is very likely we are getting a bad chain (Gavin Andresen)
This commit is contained in:
Wladimir J. van der Laan
2015-05-26 10:36:19 +02:00
parent e1412d3e96 36cba8f118
commit e9af4e65b5
4 changed files with 133 additions and 0 deletions
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59
src/main.cpp
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@@ -28,6 +28,7 @@
#include <boost/algorithm/string/replace.hpp>
#include <boost/filesystem.hpp>
#include <boost/filesystem/fstream.hpp>
#include <boost/math/distributions/poisson.hpp>
#include <boost/thread.hpp>
using namespace std;
@@ -1685,6 +1686,64 @@ void ThreadScriptCheck() {
scriptcheckqueue.Thread();
}
//
// Called periodically asynchronously; alerts if it smells like
// we're being fed a bad chain (blocks being generated much
// too slowly or too quickly).
//
void PartitionCheck(bool (*initialDownloadCheck)(), CCriticalSection& cs, const CChain& chain, int64_t nPowTargetSpacing)
{
if (initialDownloadCheck()) return;
static int64_t lastAlertTime = 0;
int64_t now = GetAdjustedTime();
if (lastAlertTime > now-60*60*24) return; // Alert at most once per day
const int SPAN_HOURS=4;
const int SPAN_SECONDS=SPAN_HOURS*60*60;
int BLOCKS_EXPECTED = SPAN_SECONDS / nPowTargetSpacing;
boost::math::poisson_distribution<double> poisson(BLOCKS_EXPECTED);
std::string strWarning;
int64_t startTime = GetAdjustedTime()-SPAN_SECONDS;
LOCK(cs);
int h = chain.Height();
while (h > 0 && chain[h]->GetBlockTime() >= startTime)
--h;
int nBlocks = chain.Height()-h;
// How likely is it to find that many by chance?
double p = boost::math::pdf(poisson, nBlocks);
LogPrint("partitioncheck", "%s : Found %d blocks in the last %d hours\n", __func__, nBlocks, SPAN_HOURS);
LogPrint("partitioncheck", "%s : likelihood: %g\n", __func__, p);
// Aim for one false-positive about every fifty years of normal running:
const int FIFTY_YEARS = 50*365*24*60*60;
double alertThreshold = 1.0 / (FIFTY_YEARS / SPAN_SECONDS);
if (p <= alertThreshold && nBlocks < BLOCKS_EXPECTED)
{
// Many fewer blocks than expected: alert!
strWarning = strprintf(_("WARNING: check your network connection, %d blocks received in the last %d hours (%d expected)"),
nBlocks, SPAN_HOURS, BLOCKS_EXPECTED);
}
else if (p <= alertThreshold && nBlocks > BLOCKS_EXPECTED)
{
// Many more blocks than expected: alert!
strWarning = strprintf(_("WARNING: abnormally high number of blocks generated, %d blocks received in the last %d hours (%d expected)"),
nBlocks, SPAN_HOURS, BLOCKS_EXPECTED);
}
if (!strWarning.empty())
{
strMiscWarning = strWarning;
CAlert::Notify(strWarning, true);
lastAlertTime = now;
}
}
static int64_t nTimeVerify = 0;
static int64_t nTimeConnect = 0;
static int64_t nTimeIndex = 0;