Merge pull request #6224

59b49cd Eliminate signed/unsigned comparison warning (Suhas Daftuar)
04b5d23 Replace sleep with syncing using pings (Suhas Daftuar)
6b1066f Ignore whitelisting during IBD for unrequested blocks. (Suhas Daftuar)
bfc30b3 Ignore unrequested blocks too far ahead of tip (Suhas Daftuar)

1 files changed, 14 insertions, 3 deletions

diff --git a/src/main.cpp b/src/main.cpp
index fefeabeb64..d470ba9003 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2734,9 +2734,15 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
 
     // Try to process all requested blocks that we don't have, but only
     // process an unrequested block if it's new and has enough work to
-    // advance our tip.
+    // advance our tip, and isn't too many blocks ahead.
     bool fAlreadyHave = pindex->nStatus & BLOCK_HAVE_DATA;
     bool fHasMoreWork = (chainActive.Tip() ? pindex->nChainWork > chainActive.Tip()->nChainWork : true);
+    // Blocks that are too out-of-order needlessly limit the effectiveness of
+    // pruning, because pruning will not delete block files that contain any
+    // blocks which are too close in height to the tip.  Apply this test
+    // regardless of whether pruning is enabled; it should generally be safe to
+    // not process unrequested blocks.
+    bool fTooFarAhead = (pindex->nHeight > int(chainActive.Height() + MIN_BLOCKS_TO_KEEP));
 
     // TODO: deal better with return value and error conditions for duplicate
     // and unrequested blocks.
@@ -2744,6 +2750,7 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
     if (!fRequested) {  // If we didn't ask for it:
         if (pindex->nTx != 0) return true;  // This is a previously-processed block that was pruned
         if (!fHasMoreWork) return true;     // Don't process less-work chains
+        if (fTooFarAhead) return true;      // Block height is too high
     }
 
     if ((!CheckBlock(block, state)) || !ContextualCheckBlock(block, state, pindex->pprev)) {
@@ -4368,8 +4375,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         pfrom->AddInventoryKnown(inv);
 
         CValidationState state;
-        // Process all blocks from whitelisted peers, even if not requested.
-        ProcessNewBlock(state, pfrom, &block, pfrom->fWhitelisted, NULL);
+        // Process all blocks from whitelisted peers, even if not requested,
+        // unless we're still syncing with the network.
+        // Such an unrequested block may still be processed, subject to the
+        // conditions in AcceptBlock().
+        bool forceProcessing = pfrom->fWhitelisted && !IsInitialBlockDownload();
+        ProcessNewBlock(state, pfrom, &block, forceProcessing, NULL);
         int nDoS;
         if (state.IsInvalid(nDoS)) {
             pfrom->PushMessage("reject", strCommand, state.GetRejectCode(),