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Fix an issue in block chain handling, whereby a duplicate block received that was not the chain head could result in wallet corruption and bogus "block forks the chain" messages. Resolves issue 135.

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This commit is contained in:
Mike Hearn 2012-02-13 21:36:09 +01:00
parent a70c868f3f
commit 57d518aba9
2 changed files with 52 additions and 9 deletions
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25
src/com/google/bitcoin/core/BlockChain.java
View File

@ -153,6 +153,7 @@ public class BlockChain {
// We check only the chain head for double adds here to avoid potentially expensive block chain misses.
if (block.equals(chainHead.getHeader())) {
// Duplicate add of the block at the top of the chain, can be a natural artifact of the download process.
log.debug("Chain head added more than once: {}", block.getHash());
return true;
}
@ -187,6 +188,7 @@ public class BlockChain {
// We can't find the previous block. Probably we are still in the process of downloading the chain and a
// block was solved whilst we were doing it. We put it to one side and try to connect it later when we
// have more blocks.
assert tryConnecting : "bug in tryConnectingUnconnected";
log.warn("Block does not connect: {}", block.getHashAsString());
unconnectedBlocks.add(block);
return false;
@ -227,14 +229,24 @@ public class BlockChain {
log.info("Block is causing a re-organize");
} else {
StoredBlock splitPoint = findSplit(newStoredBlock, chainHead);
if (splitPoint == newStoredBlock) {
// newStoredBlock is a part of the same chain, there's no fork. This happens when we receive a block
// that we already saw and linked into the chain previously, which isn't the chain head.
// Re-processing it is confusing for the wallet so just skip.
log.debug("Saw duplicated block in main chain at height {}: {}",
newStoredBlock.getHeight(), newStoredBlock.getHeader().getHash());
return;
}
int splitPointHeight = splitPoint != null ? splitPoint.getHeight() : -1;
String splitPointHash =
splitPoint != null ? splitPoint.getHeader().getHashAsString() : "?";
log.info("Block forks the chain at {}, but it did not cause a reorganize:\n{}",
splitPointHash, newStoredBlock);
log.info("Block forks the chain at height {}/block {}, but it did not cause a reorganize:\n{}",
new Object[]{splitPointHeight, splitPointHash, newStoredBlock});
}
// We may not have any transactions if we received only a header. That never happens today but will in
// future when getheaders is used as an optimization.
// We may not have any transactions if we received only a header, which can happen during fast catchup.
// If we do, send them to the wallet but state that they are on a side chain so it knows not to try and
// spend them until they become activated.
if (newTransactions != null) {
sendTransactionsToWallet(newStoredBlock, NewBlockType.SIDE_CHAIN, newTransactions);
}
@ -288,7 +300,8 @@ public class BlockChain {
/**
* Locates the point in the chain at which newStoredBlock and chainHead diverge. Returns null if no split point was
* found (ie they are part of the same chain).
* found (ie they are not part of the same chain). Returns newChainHead or chainHead if they don't actually diverge
* but are part of the same chain.
*/
private StoredBlock findSplit(StoredBlock newChainHead, StoredBlock chainHead) throws BlockStoreException {
StoredBlock currentChainCursor = chainHead;
@ -359,10 +372,12 @@ public class BlockChain {
Iterator<Block> iter = unconnectedBlocks.iterator();
while (iter.hasNext()) {
Block block = iter.next();
log.debug("Trying to connect {}", block.getHash());
// Look up the blocks previous.
StoredBlock prev = blockStore.get(block.getPrevBlockHash());
if (prev == null) {
// This is still an unconnected/orphan block.
log.debug(" but it is not connectable right now");
continue;
}
// Otherwise we can connect it now.

36
tests/com/google/bitcoin/core/BlockChainTest.java
View File

@ -18,6 +18,7 @@ package com.google.bitcoin.core;
import com.google.bitcoin.store.BlockStore;
import com.google.bitcoin.store.MemoryBlockStore;
import com.google.bitcoin.utils.BriefLogFormatter;
import org.junit.Before;
import org.junit.Test;
@ -38,6 +39,7 @@ public class BlockChainTest {
private BlockStore blockStore;
private Address coinbaseTo;
private NetworkParameters unitTestParams;
private final StoredBlock[] block = new StoredBlock[1];
private void resetBlockStore() {
blockStore = new MemoryBlockStore(unitTestParams);
@ -45,9 +47,16 @@ public class BlockChainTest {
@Before
public void setUp() throws Exception {
BriefLogFormatter.initVerbose();
testNetChain = new BlockChain(testNet, new Wallet(testNet), new MemoryBlockStore(testNet));
unitTestParams = NetworkParameters.unitTests();
wallet = new Wallet(unitTestParams);
wallet = new Wallet(unitTestParams) {
@Override
public void receiveFromBlock(Transaction tx, StoredBlock block, BlockChain.NewBlockType blockType) throws VerificationException, ScriptException {
super.receiveFromBlock(tx, block, blockType);
BlockChainTest.this.block[0] = block;
}
};
wallet.addKey(new ECKey());
resetBlockStore();
@ -120,7 +129,7 @@ public class BlockChainTest {
}
@Test
public void testUnconnectedBlocks() throws Exception {
public void unconnectedBlocks() throws Exception {
Block b1 = unitTestParams.genesisBlock.createNextBlock(coinbaseTo);
Block b2 = b1.createNextBlock(coinbaseTo);
Block b3 = b2.createNextBlock(coinbaseTo);
@ -135,7 +144,7 @@ public class BlockChainTest {
}
@Test
public void testDifficultyTransitions() throws Exception {
public void difficultyTransitions() throws Exception {
// Add a bunch of blocks in a loop until we reach a difficulty transition point. The unit test params have an
// artificially shortened period.
Block prev = unitTestParams.genesisBlock;
@ -163,7 +172,7 @@ public class BlockChainTest {
}
@Test
public void testBadDifficulty() throws Exception {
public void badDifficulty() throws Exception {
assertTrue(testNetChain.add(getBlock1()));
Block b2 = getBlock2();
assertTrue(testNetChain.add(b2));
@ -202,6 +211,25 @@ public class BlockChainTest {
// TODO: Test difficulty change is not out of range when a transition period becomes valid.
}
@Test
public void duplicates() throws Exception {
// Adding a block twice should not have any effect, in particular it should not send the block to the wallet.
Block b1 = unitTestParams.genesisBlock.createNextBlock(coinbaseTo);
Block b2 = b1.createNextBlock(coinbaseTo);
Block b3 = b2.createNextBlock(coinbaseTo);
assertTrue(chain.add(b1));
assertEquals(b1, block[0].getHeader());
assertTrue(chain.add(b2));
assertEquals(b2, block[0].getHeader());
assertTrue(chain.add(b3));
assertEquals(b3, block[0].getHeader());
assertEquals(b3, chain.getChainHead().getHeader());
assertTrue(chain.add(b2));
assertEquals(b3, chain.getChainHead().getHeader());
// Wallet was NOT called with the new block because the duplicate add was spotted.
assertEquals(b3, block[0].getHeader());
}
// Some blocks from the test net.
private Block getBlock2() throws Exception {
Block b2 = new Block(testNet);