private ConcurrentDictionary<COutPoint, uint> mapStakeSeen = new ConcurrentDictionary<COutPoint, uint>();
- private ConcurrentDictionary<COutPoint, uint> mapStakeSeenOrphan = new ConcurrentDictionary<COutPoint, uint>();
+ private ConcurrentDictionary<Tuple<COutPoint, uint>, uint256> mapStakeSeenOrphan = new ConcurrentDictionary<Tuple<COutPoint, uint>, uint256>();
/// <summary>
{
if (block.IsProofOfStake)
{
- // TODO: limit duplicity on stake
+ var proof = block.ProofOfStake;
+
+ // Limited duplicity on stake: prevents block flood attack
+ // Duplicate stake allowed only when there is orphan child block
+ if (mapStakeSeenOrphan.ContainsKey(proof) && !orphanMapByPrev.ContainsKey(blockHash))
+ {
+ return false; // duplicate proof-of-stake
+ }
+ else
+ {
+ mapStakeSeenOrphan.TryAdd(proof, blockHash);
+ }
}
- var block2 = new CBlock(block);
- orphanMap.TryAdd(blockHash, block2);
- orphanMapByPrev.TryAdd(blockHash, block2);
+ orphanMap.TryAdd(blockHash, block);
+ orphanMapByPrev.TryAdd(blockHash, block);
return true;
}
return false;
}
- // Recursively process any orphan blocks that depended on this one
- var orphansQueue = new List<uint256>();
- orphansQueue.Add(blockHash);
-
- for (int i = 0; i < orphansQueue.Count; i++)
+ if (orphanMapByPrev.Count > 0)
{
- var hashPrev = orphansQueue[i];
+ // Recursively process any orphan blocks that depended on this one
+
+ var orphansQueue = new List<uint256>();
+ orphansQueue.Add(blockHash);
- foreach (var pair in orphanMap)
+ for (int i = 0; i < orphansQueue.Count; i++)
{
- var orphanBlock = pair.Value;
+ var hashPrev = orphansQueue[i];
- if (orphanBlock.header.prevHash == blockHash)
+ foreach (var pair in orphanMapByPrev)
{
- if (AcceptBlock(ref orphanBlock))
+ var orphanBlock = pair.Value;
+
+ if (orphanBlock.header.prevHash == blockHash)
{
- orphansQueue.Add(pair.Key);
- }
+ if (AcceptBlock(ref orphanBlock))
+ {
+ orphansQueue.Add(pair.Key);
+ }
- CBlock dummy1;
- orphanMap.TryRemove(pair.Key, out dummy1);
+ CBlock dummy1;
+ orphanMap.TryRemove(pair.Key, out dummy1);
+
+ uint256 dummyHash;
+ mapStakeSeenOrphan.TryRemove(orphanBlock.ProofOfStake, out dummyHash);
+ }
}
- }
- CBlock dummy2;
- orphanMap.TryRemove(hashPrev, out dummy2);
+ CBlock dummy2;
+ orphanMapByPrev.TryRemove(hashPrev, out dummy2);
+ }
}
return true;