diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/net_processing.cpp | 17 | ||||
| -rw-r--r-- | src/validation.cpp | 6 |
2 files changed, 21 insertions, 2 deletions
diff --git a/src/net_processing.cpp b/src/net_processing.cpp index 6c26cd4cee..61f98ca747 100644 --- a/src/net_processing.cpp +++ b/src/net_processing.cpp @@ -2146,7 +2146,16 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr mapBlockSource.emplace(pblock->GetHash(), std::make_pair(pfrom->GetId(), false)); } bool fNewBlock = false; - ProcessNewBlock(chainparams, pblock, true, &fNewBlock); + // Setting fForceProcessing to true means that we bypass some of + // our anti-DoS protections in AcceptBlock, which filters + // unrequested blocks that might be trying to waste our resources + // (eg disk space). Because we only try to reconstruct blocks when + // we're close to caught up (via the CanDirectFetch() requirement + // above, combined with the behavior of not requesting blocks until + // we have a chain with at least nMinimumChainWork), and we ignore + // compact blocks with less work than our tip, it is safe to treat + // reconstructed compact blocks as having been requested. + ProcessNewBlock(chainparams, pblock, /*fForceProcessing=*/true, &fNewBlock); if (fNewBlock) { pfrom->nLastBlockTime = GetTime(); } else { @@ -2226,7 +2235,11 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr bool fNewBlock = false; // Since we requested this block (it was in mapBlocksInFlight), force it to be processed, // even if it would not be a candidate for new tip (missing previous block, chain not long enough, etc) - ProcessNewBlock(chainparams, pblock, true, &fNewBlock); + // This bypasses some anti-DoS logic in AcceptBlock (eg to prevent + // disk-space attacks), but this should be safe due to the + // protections in the compact block handler -- see related comment + // in compact block optimistic reconstruction handling. + ProcessNewBlock(chainparams, pblock, /*fForceProcessing=*/true, &fNewBlock); if (fNewBlock) { pfrom->nLastBlockTime = GetTime(); } else { diff --git a/src/validation.cpp b/src/validation.cpp index d19521bd3c..866e0c9fba 100644 --- a/src/validation.cpp +++ b/src/validation.cpp @@ -3135,6 +3135,12 @@ static bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidation if (pindex->nTx != 0) return true; // This is a previously-processed block that was pruned if (!fHasMoreWork) return true; // Don't process less-work chains if (fTooFarAhead) return true; // Block height is too high + + // Protect against DoS attacks from low-work chains. + // If our tip is behind, a peer could try to send us + // low-work blocks on a fake chain that we would never + // request; don't process these. + if (pindex->nChainWork < nMinimumChainWork) return true; } if (fNewBlock) *fNewBlock = true; |