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Allow compactblock reconstruction when block is in flight

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This commit is contained in:
Suhas Daftuar
2016-12-14 17:00:06 -05:00
parent 0a4aa87623
commit 4ced313256
1 changed files with 49 additions and 0 deletions
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49
src/main.cpp
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@@ -5657,6 +5657,11 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
CBlockHeaderAndShortTxIDs cmpctblock;
vRecv >> cmpctblock;
// Keep a CBlock for "optimistic" compactblock reconstructions (see
// below)
CBlock block;
bool fBlockReconstructed = false;
LOCK(cs_main);
if (mapBlockIndex.find(cmpctblock.header.hashPrevBlock) == mapBlockIndex.end()) {
@@ -5765,6 +5770,23 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
req.blockhash = pindex->GetBlockHash();
pfrom->PushMessage(NetMsgType::GETBLOCKTXN, req);
}
} else {
// This block is either already in flight from a different
// peer, or this peer has too many blocks outstanding to
// download from.
// Optimistically try to reconstruct anyway since we might be
// able to without any round trips.
PartiallyDownloadedBlock tempBlock(&mempool);
ReadStatus status = tempBlock.InitData(cmpctblock);
if (status != READ_STATUS_OK) {
// TODO: don't ignore failures
return true;
}
std::vector<CTransaction> dummy;
status = tempBlock.FillBlock(block, dummy);
if (status == READ_STATUS_OK) {
fBlockReconstructed = true;
}
}
} else {
if (fAlreadyInFlight) {
@@ -5785,6 +5807,33 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
}
}
if (fBlockReconstructed) {
// If we got here, we were able to optimistically reconstruct a
// block that is in flight from some other peer. However, this
// cmpctblock may be invalid. In particular, while we've checked
// that the block merkle root commits to the transaction ids, we
// haven't yet checked that tx witnesses are properly committed to
// in the coinbase witness commitment.
//
// ProcessNewBlock will call MarkBlockAsReceived(), which will
// clear any in-flight compact block state that might be present
// from some other peer. We don't want a malleated compact block
// request to interfere with block relay, so we don't want to call
// ProcessNewBlock until we've already checked that the witness
// commitment is correct.
{
LOCK(cs_main);
CValidationState dummy;
if (!ContextualCheckBlock(block, dummy, pindex->pprev)) {
// TODO: could send reject message to peer?
return true;
}
}
CValidationState state;
ProcessNewBlock(state, chainparams, pfrom, &block, true, NULL, false);
// TODO: could send reject message if block is invalid?
}
CheckBlockIndex(chainparams.GetConsensus());
}