Merge pull request #314 from Asherda/inv-buffer

Backport fix for INV buffer

Author: miketout

src/main.cpp

@@ -3135,7 +3135,7 @@ namespace Consensus {
         {
             outOverflow = true;
         }
-        
+
         if (outOverflow || ReserveValueIn < reserveValueOut)
         {
             fprintf(stderr,"overflow or spentheight.%d reservevaluein: %s\nis less than out: %s\n", nSpendHeight,
@@ -8806,7 +8806,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
 
         LOCK(cs_main);
 
-        std::vector<CInv> vToFetch;
+        const uint256* best_block{nullptr};
 
         for (unsigned int nInv = 0; nInv < vInv.size(); nInv++)
         {
@@ -8820,29 +8820,14 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
             if (inv.type == MSG_BLOCK) {
                 UpdateBlockAvailability(pfrom->GetId(), inv.hash);
                 if (!fAlreadyHave && !fImporting && !fReindex && !mapBlocksInFlight.count(inv.hash)) {
-                    // First request the headers preceding the announced block. In the normal fully-synced
-                    // case where a new block is announced that succeeds the current tip (no reorganization),
-                    // there are no such headers.
-                    // Secondly, and only when we are close to being synced, we request the announced block directly,
-                    // to avoid an extra round-trip. Note that we must *first* ask for the headers, so by the
-                    // time the block arrives, the header chain leading up to it is already validated. Not
-                    // doing this will result in the received block being rejected as an orphan in case it is
-                    // not a direct successor.
-                    pfrom->PushMessage("getheaders", chainActive.GetLocator(pindexBestHeader), inv.hash);
-                    CNodeState *nodestate = State(pfrom->GetId());
-
-                    if (chainActive.Tip()->GetBlockTime() > GetAdjustedTime() - (ConnectedChains.ThisChain().blockTime * 20) &&
-                        nodestate->nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
-                        vToFetch.push_back(inv);
-                        // Mark block as in flight already, even though the actual "getdata" message only goes out
-                        // later (within the same cs_main lock, though).
-                        MarkBlockAsInFlight(pfrom->GetId(), inv.hash, chainparams.GetConsensus());
-                    }
-                    LogPrint("net", "getheaders (%d) %s to peer=%d\n", pindexBestHeader->GetHeight(), inv.hash.ToString(), pfrom->id);
+                    // Headers-first is the primary method of announcement on
+                    // the network. If a node fell back to sending blocks by inv,
+                    // it's probably for a re-org. The final block hash
+                    // provided should be the highest, so send a getheaders and
+                    // then fetch the blocks we need to catch up.
+                    best_block = &inv.hash;
                 }
-            }
-            else
-            {
+            } else {
                 pfrom->AddKnownWTxId(WTxId(inv.hash));
                 if (fBlocksOnly)
                     LogPrint("net", "transaction (%s) inv sent in violation of protocol peer=%d\n", inv.hash.ToString(), pfrom->id);
@@ -8856,8 +8841,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
             }
         }
 
-        if (!vToFetch.empty())
-            pfrom->PushMessage("getdata", vToFetch);
+        if (best_block != nullptr) {
+            pfrom->PushMessage("getheaders", chainActive.GetLocator(pindexBestHeader), *best_block);
+            LogPrint("net", "getheaders (%d) %s to peer=%d\n", pindexBestHeader->GetHeight(), best_block->ToString(), pfrom->id);
+        }
     }
 
 
@@ -9125,7 +9112,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
             LogPrint("mempool", "%s from peer=%d %s was not accepted into the memory pool: %s\n", tx.GetHash().ToString(),
                      pfrom->id, pfrom->cleanSubVer,
                      state.GetRejectReason());
-            
+
             bool sendReject = true;
             if (state.GetRejectReason() == "bad-txns-inputs-spent" && nDoS <= 1)
             {