Use best header chain timestamps to detect partitioning

The partition checking code was using chainActive timestamps
to detect partitioning; with headers-first syncing, it should use
(and with this pull request, does use) pIndexBestHeader timestamps.

Fixes issue #6251

Github-Pull: #6256
Rebased-From: 65b94545036ae6e38e79e9c7166a3ba1ddb83f66

1 files changed, 10 insertions, 6 deletions

diff --git a/src/main.cpp b/src/main.cpp
index ae9e57557..e08c3df9f 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1712,9 +1712,10 @@ void ThreadScriptCheck() {
 // 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)
+void PartitionCheck(bool (*initialDownloadCheck)(), CCriticalSection& cs, const CBlockIndex *const &bestHeader,
+                    int64_t nPowTargetSpacing)
 {
-    if (initialDownloadCheck()) return;
+    if (bestHeader == NULL || initialDownloadCheck()) return;
 
     static int64_t lastAlertTime = 0;
     int64_t now = GetAdjustedTime();
@@ -1730,10 +1731,13 @@ void PartitionCheck(bool (*initialDownloadCheck)(), CCriticalSection& cs, const
     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;
+    const CBlockIndex* i = bestHeader;
+    int nBlocks = 0;
+    while (i->GetBlockTime() >= startTime) {
+        ++nBlocks;
+        i = i->pprev;
+        if (i == NULL) return; // Ran out of chain, we must not be fully sync'ed
+    }
 
     // How likely is it to find that many by chance?
     double p = boost::math::pdf(poisson, nBlocks);