From 686013337339cbcfe0966e662c59fcdb3c22c108 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Sat, 5 May 2012 04:04:38 +0200 Subject: [PATCH] Prevent stuck download: correct solution Pull request #948 introduced a fix for nodes stuck on a long side branch of the main chain. The fix was non-functional however, as the additional getdata request was created in a first step of processing, but dropped in a second step as it was considered redundant. This commits fixes it by sending the request directly. --- src/main.cpp | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/src/main.cpp b/src/main.cpp index c1c57d1d2b..821bfbb476 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -2391,6 +2391,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv) return error("message inv size() = %d", vInv.size()); } + // find last block in inv vector + unsigned int nLastBlock = (unsigned int)(-1); + for (unsigned int nInv = 0; nInv < vInv.size(); nInv++) { + if (vInv[vInv.size() - 1 - nInv].type == MSG_BLOCK) + nLastBlock = vInv.size() - 1 - nInv; + } CTxDB txdb("r"); for (unsigned int nInv = 0; nInv < vInv.size(); nInv++) { @@ -2407,9 +2413,15 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv) // Always request the last block in an inv bundle (even if we already have it), as it is the // trigger for the other side to send further invs. If we are stuck on a (very long) side chain, // this is necessary to connect earlier received orphan blocks to the chain again. - if (!fAlreadyHave || (inv.type == MSG_BLOCK && nInv==vInv.size()-1)) + if (fAlreadyHave && nInv == nLastBlock) { + // bypass mapAskFor, and send request directly; it must go through. + std::vector vGetData(1,inv); + pfrom->PushMessage("getdata", vGetData); + } + + if (!fAlreadyHave) pfrom->AskFor(inv); - if (inv.type == MSG_BLOCK && mapOrphanBlocks.count(inv.hash)) + else if (inv.type == MSG_BLOCK && mapOrphanBlocks.count(inv.hash)) pfrom->PushGetBlocks(pindexBest, GetOrphanRoot(mapOrphanBlocks[inv.hash])); // Track requests for our stuff