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Merge pull request #915 from sipa/nooverwritetx

Do not allow overwriting unspent transactions
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gavinandresen committed Mar 3, 2012
2 parents 50abb55 + a206b0e commit f2e81bad3353742952e78b89b569da1805c1d6b2
Showing with 24 additions and 2 deletions.
  1. +24 −2 src/main.cpp
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@@ -976,8 +976,10 @@ bool CTransaction::DisconnectInputs(CTxDB& txdb)
}
// Remove transaction from index
if (!txdb.EraseTxIndex(*this))
return error("DisconnectInputs() : EraseTxPos failed");
// This can fail if a duplicate of this transaction was in a chain that got
// reorganized away. This is only possible if this transaction was completely
// spent, so erasing it would be a no-op anway.
txdb.EraseTxIndex(*this);
return true;
}
@@ -1256,6 +1258,26 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex)
if (!CheckBlock())
return false;
// Do not allow blocks that contain transactions which 'overwrite' older transactions,
// unless those are already completely spent.
// If such overwrites are allowed, coinbases and transactions depending upon those
// can be duplicated to remove the ability to spend the first instance -- even after
// being sent to another address.
// See BIP30 and http://r6.ca/blog/20120206T005236Z.html for more information.
// This logic is not necessary for memory pool transactions, as AcceptToMemoryPool
// already refuses previously-known transaction id's entirely.
// This rule applies to all blocks whose timestamp is after March 15, 2012, 0:00 UTC.
// On testnet it is enabled as of februari 20, 2012, 0:00 UTC.
if (pindex->nTime > 1331769600 || (fTestNet && pindex->nTime > 1329696000))
BOOST_FOREACH(CTransaction& tx, vtx)
{
CTxIndex txindexOld;
if (txdb.ReadTxIndex(tx.GetHash(), txindexOld))
BOOST_FOREACH(CDiskTxPos &pos, txindexOld.vSpent)
if (pos.IsNull())
return false;
}
// To avoid being on the short end of a block-chain split,
// don't do secondary validation of pay-to-script-hash transactions
// until blocks with timestamps after paytoscripthashtime (see init.cpp for default).

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