Merge 04b943b63c into b510893d00

The existing IBD check was added at a time when CheckForkWarningConditions
did also sophisticated fork detection that could lead to false positives
during IBD (55ed3f1475).

The fork detection logic doesn't exist anymore
(since fa62304c97), so the IBD check is no
longer necessary.

Displaying the log at startup will help node operators diagnose the
problem better.

src/net_processing.cpp

@@ -2956,6 +2956,12 @@ void PeerManagerImpl::ProcessHeadersMessage(CNode& pfrom, Peer& peer,
                                                            state, &pindexLast)};
     if (!processed) {
         if (state.IsInvalid()) {
+            if (!pfrom.IsInboundConn() && state.GetResult() == BlockValidationResult::BLOCK_CACHED_INVALID) {
+                LogWarning("Header received from peer=%i was previously marked as invalid. "
+                           "If this happens with all peers, database corruption is likely and "
+                           "-reindex may be necessary to recover.",
+                           pfrom.GetId());
+            }
             MaybePunishNodeForBlock(pfrom.GetId(), state, via_compact_block, "invalid header received");
             return;
         }

src/validation.cpp

@@ -2023,15 +2023,12 @@ void Chainstate::CheckForkWarningConditions()
 {
     AssertLockHeld(cs_main);
 
-    // Before we get past initial download, we cannot reliably alert about forks
+    if (this->GetRole() == ChainstateRole::BACKGROUND) {
-    // (we assume we don't get stuck on a fork before finishing our initial sync)
-    // Also not applicable to the background chainstate
-    if (m_chainman.IsInitialBlockDownload() || this->GetRole() == ChainstateRole::BACKGROUND) {
         return;
     }
 
     if (m_chainman.m_best_invalid && m_chainman.m_best_invalid->nChainWork > m_chain.Tip()->nChainWork + (GetBlockProof(*m_chain.Tip()) * 6)) {
-        LogPrintf("%s: Warning: Found invalid chain at least ~6 blocks longer than our best chain.\nChain state database corruption likely.\n", __func__);
+        LogWarning("Found invalid chain at least ~6 blocks longer than our best chain. Chain state database corruption likely.");
         m_chainman.GetNotifications().warningSet(
             kernel::Warning::LARGE_WORK_INVALID_CHAIN,
             _("Warning: We do not appear to fully agree with our peers! You may need to upgrade, or other nodes may need to upgrade."));
@@ -4674,6 +4671,8 @@ bool Chainstate::LoadChainTip()
             /*verification_progress=*/m_chainman.GuessVerificationProgress(tip));
     }
 
+    CheckForkWarningConditions();
+
     return true;
 }