net processing: Only send a getheaders for one block in an bitcoin/bi…

…tcoin#18962
DeFiCh · Oct 8, 2024 · fe3d20f · fe3d20f
1 parent 3fda764
commit fe3d20f
Showing 1 changed file with 13 additions and 7 deletions.
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
@@ -2341,6 +2341,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
 
         uint32_t nFetchFlags = GetFetchFlags(pfrom);
         const auto current_time = GetTime<std::chrono::microseconds>();
+        uint256* best_block{nullptr};
 
         for (CInv &inv : vInv)
         {
@@ -2357,13 +2358,12 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             if (inv.type == MSG_BLOCK) {
                 UpdateBlockAvailability(pfrom->GetId(), inv.hash);
                 if (!fAlreadyHave && !fImporting && !fReindex && !mapBlocksInFlight.count(inv.hash)) {
-                    // We used to request the full block here, but since headers-announcements are now the
-                    // primary method of announcement on the network, and since, in the case that a node
-                    // fell back to inv we probably have a reorg which we should get the headers for first,
-                    // we now only provide a getheaders response here. When we receive the headers, we will
-                    // then ask for the blocks we need.
-                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETHEADERS, ::ChainActive().GetLocator(pindexBestHeader), inv.hash));
-                    LogPrint(BCLog::NET, "getheaders (%d) %s to peer=%d\n", pindexBestHeader->nHeight, inv.hash.ToString(), pfrom->GetId());
+                    // 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 if (inv.type == MSG_ANCHOR_AUTH) {
@@ -2386,6 +2386,12 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
                 }
             }
         }
+
+        if (best_block != nullptr) {
+            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETHEADERS, ::ChainActive().GetLocator(pindexBestHeader), *best_block));
+            LogPrint(BCLog::NET, "getheaders (%d) %s to peer=%d\n", pindexBestHeader->nHeight, best_block->ToString(), pfrom->GetId());
+        }
+
         return true;
     }