diff --git a/src/main.cpp b/src/main.cpp index a1c027bef38c5..86cc5afc027bb 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -5084,6 +5084,13 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv, return true; } + // If we already know the last header in the message, then it contains + // no new information for us. In this case, we do not request + // more headers later. This prevents multiple chains of redundant + // getheader requests from running in parallel if triggered by incoming + // blocks while the node is still in initial headers sync. + const bool hasNewHeaders = (mapBlockIndex.count(headers.back().GetHash()) == 0); + CBlockIndex *pindexLast = NULL; BOOST_FOREACH(const CBlockHeader& header, headers) { CValidationState state; @@ -5104,7 +5111,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv, if (pindexLast) UpdateBlockAvailability(pfrom->GetId(), pindexLast->GetBlockHash()); - if (nCount == MAX_HEADERS_RESULTS && pindexLast) { + if (nCount == MAX_HEADERS_RESULTS && pindexLast && hasNewHeaders) { // Headers message had its maximum size; the peer may have more headers. // TODO: optimize: if pindexLast is an ancestor of chainActive.Tip or pindexBestHeader, continue // from there instead.