Merge pull request #6148

ae6f957 Enable block relay when pruning (Suhas Daftuar)
0da6ae2 Do not inv old or missing blocks when pruning (Suhas Daftuar)

src/main.cpp

@@ -2315,9 +2315,7 @@ bool ActivateBestChain(CValidationState &state, const CBlock *pblock) {
             int nBlockEstimate = 0;
             if (fCheckpointsEnabled)
                 nBlockEstimate = Checkpoints::GetTotalBlocksEstimate(chainParams.Checkpoints());
-            // Don't relay blocks if pruning -- could cause a peer to try to download, resulting
-            // in a stalled download if the block file is pruned before the request.
-            if (nLocalServices & NODE_NETWORK) {
+            {
                 LOCK(cs_vNodes);
                 BOOST_FOREACH(CNode* pnode, vNodes)
                     if (chainActive.Height() > (pnode->nStartingHeight != -1 ? pnode->nStartingHeight - 2000 : nBlockEstimate))
@@ -4198,6 +4196,14 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
                 LogPrint("net", "  getblocks stopping at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
                 break;
             }
+            // If pruning, don't inv blocks unless we have on disk and are likely to still have
+            // for some reasonable time window (1 hour) that block relay might require.
+            const int nPrunedBlocksLikelyToHave = MIN_BLOCKS_TO_KEEP - 3600 / chainparams.GetConsensus().nPowTargetSpacing;
+            if (fPruneMode && (!(pindex->nStatus & BLOCK_HAVE_DATA) || pindex->nHeight <= chainActive.Tip()->nHeight - nPrunedBlocksLikelyToHave))
+            {
+                LogPrint("net", " getblocks stopping, pruned or too old block at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
+                break;
+            }
             pfrom->PushInventory(CInv(MSG_BLOCK, pindex->GetBlockHash()));
             if (--nLimit <= 0)
             {