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Add a unit test for the case where the block chain overrides a currently pending transaction. This is an edge case that should only occur when the user executes a Finney attack against somebody else.

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Fix the bug that Miron pointed out. Resolves comments on r76.
This commit is contained in:
Mike Hearn
2011-05-23 12:13:25 +00:00
parent 846412aa00
commit cb5025b987
7 changed files with 65 additions and 9 deletions
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39
tests/com/google/bitcoin/core/WalletTest.java
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@@ -208,4 +208,43 @@ public class WalletTest {
Transaction send2 = new Transaction(params, send1.bitcoinSerialize());
assertEquals(nanos, send2.getValueSentFromMe(wallet));
}
@Test
public void testFinneyAttack() throws Exception {
// A Finney attack is where a miner includes a transaction spending coins to themselves but does not
// broadcast it. When they find a solved block, they hold it back temporarily whilst they buy something with
// those same coins. After purchasing, they broadcast the block thus reversing the transaction. It can be
// done by any miner for products that can be bought at a chosen time and very quickly (as every second you
// withold your block means somebody else might find it first, invalidating your work).
//
// Test that we handle ourselves performing the attack correctly: a double spend on the chain moves
// transactions from pending to dead.
//
// Note that the other way around, where a pending transaction sending us coins becomes dead,
// isn't tested because today BitCoinJ only learns about such transactions when they appear in the chain.
final Transaction[] eventDead = new Transaction[1];
final Transaction[] eventReplacement = new Transaction[1];
wallet.addEventListener(new WalletEventListener() {
@Override
public void onDeadTransaction(Transaction deadTx, Transaction replacementTx) {
eventDead[0] = deadTx;
eventReplacement[0] = replacementTx;
}
});
// Receive 1 BTC.
BigInteger nanos = Utils.toNanoCoins(1, 0);
Transaction t1 = createFakeTx(nanos, myAddress);
wallet.receive(t1, null, BlockChain.NewBlockType.BEST_CHAIN);
// Create a send to a merchant.
Transaction send1 = wallet.createSend(new ECKey().toAddress(params), toNanoCoins(0, 50));
// Create a double spend.
Transaction send2 = wallet.createSend(new ECKey().toAddress(params), toNanoCoins(0, 50));
// Broadcast send1.
wallet.confirmSend(send1);
// Receive a block that overrides it.
wallet.receive(send2, null, BlockChain.NewBlockType.BEST_CHAIN);
assertEquals(send1, eventDead[0]);
assertEquals(send2, eventReplacement[0]);
}
}