Example #1
0
  @Test
  public void invDownloadTxMultiPeer() throws Exception {
    // Check co-ordination of which peer to download via the memory pool.
    VersionMessage ver = new VersionMessage(unitTestParams, 100);
    InetSocketAddress address = new InetSocketAddress("127.0.0.1", 4242);
    Peer peer2 = new Peer(unitTestParams, ver, new PeerAddress(address), blockChain, memoryPool);
    peer2.addWallet(wallet);
    VersionMessage peerVersion = new VersionMessage(unitTestParams, OTHER_PEER_CHAIN_HEIGHT);
    peerVersion.clientVersion = 70001;
    peerVersion.localServices = VersionMessage.NODE_NETWORK;

    connect();
    InboundMessageQueuer writeTarget2 = connect(peer2, peerVersion);

    // Make a tx and advertise it to one of the peers.
    BigInteger value = Utils.toNanoCoins(1, 0);
    Transaction tx = createFakeTx(unitTestParams, value, this.address);
    InventoryMessage inv = new InventoryMessage(unitTestParams);
    InventoryItem item = new InventoryItem(InventoryItem.Type.Transaction, tx.getHash());
    inv.addItem(item);

    inbound(writeTarget, inv);

    // We got a getdata message.
    GetDataMessage message = (GetDataMessage) outbound(writeTarget);
    assertEquals(1, message.getItems().size());
    assertEquals(tx.getHash(), message.getItems().get(0).hash);
    assertTrue(memoryPool.maybeWasSeen(tx.getHash()));

    // Advertising to peer2 results in no getdata message.
    inbound(writeTarget2, inv);
    pingAndWait(writeTarget2);
    assertNull(outbound(writeTarget2));
  }
Example #2
0
  // Check that inventory message containing blocks we want is processed correctly.
  @Test
  public void newBlock() throws Exception {
    Block b1 = createFakeBlock(blockStore).block;
    blockChain.add(b1);
    final Block b2 = makeSolvedTestBlock(b1);
    // Receive notification of a new block.
    final InventoryMessage inv = new InventoryMessage(unitTestParams);
    InventoryItem item = new InventoryItem(InventoryItem.Type.Block, b2.getHash());
    inv.addItem(item);

    final AtomicInteger newBlockMessagesReceived = new AtomicInteger(0);

    connect();
    // Round-trip a ping so that we never see the response verack if we attach too quick
    pingAndWait(writeTarget);
    peer.addEventListener(
        new AbstractPeerEventListener() {
          @Override
          public synchronized Message onPreMessageReceived(Peer p, Message m) {
            if (p != peer) fail.set(true);
            if (m instanceof Pong) return m;
            int newValue = newBlockMessagesReceived.incrementAndGet();
            if (newValue == 1 && !inv.equals(m)) fail.set(true);
            else if (newValue == 2 && !b2.equals(m)) fail.set(true);
            else if (newValue > 3) fail.set(true);
            return m;
          }

          @Override
          public synchronized void onBlocksDownloaded(Peer p, Block block, int blocksLeft) {
            int newValue = newBlockMessagesReceived.incrementAndGet();
            if (newValue != 3
                || p != peer
                || !block.equals(b2)
                || blocksLeft != OTHER_PEER_CHAIN_HEIGHT - 2) fail.set(true);
          }
        },
        Threading.SAME_THREAD);
    long height = peer.getBestHeight();

    inbound(writeTarget, inv);
    pingAndWait(writeTarget);
    assertEquals(height + 1, peer.getBestHeight());
    // Response to the getdata message.
    inbound(writeTarget, b2);

    pingAndWait(writeTarget);
    Threading.waitForUserCode();
    pingAndWait(writeTarget);
    assertEquals(3, newBlockMessagesReceived.get());

    GetDataMessage getdata = (GetDataMessage) outbound(writeTarget);
    List<InventoryItem> items = getdata.getItems();
    assertEquals(1, items.size());
    assertEquals(b2.getHash(), items.get(0).hash);
    assertEquals(InventoryItem.Type.Block, items.get(0).type);
  }
Example #3
0
  @Test
  public void fastCatchup() throws Exception {
    connect();

    // Check that blocks before the fast catchup point are retrieved using getheaders, and after
    // using getblocks.
    // This test is INCOMPLETE because it does not check we handle >2000 blocks correctly.
    Block b1 = createFakeBlock(blockStore).block;
    blockChain.add(b1);
    Utils.rollMockClock(60 * 10); // 10 minutes later.
    Block b2 = makeSolvedTestBlock(b1);
    Utils.rollMockClock(60 * 10); // 10 minutes later.
    Block b3 = makeSolvedTestBlock(b2);
    Utils.rollMockClock(60 * 10);
    Block b4 = makeSolvedTestBlock(b3);

    // Request headers until the last 2 blocks.
    peer.setDownloadParameters((Utils.now().getTime() / 1000) - (600 * 2) + 1, false);
    peer.startBlockChainDownload();
    GetHeadersMessage getheaders = (GetHeadersMessage) outbound(writeTarget);
    List<Sha256Hash> expectedLocator = new ArrayList<Sha256Hash>();
    expectedLocator.add(b1.getHash());
    expectedLocator.add(unitTestParams.getGenesisBlock().getHash());
    assertEquals(getheaders.getLocator(), expectedLocator);
    assertEquals(getheaders.getStopHash(), Sha256Hash.ZERO_HASH);
    // Now send all the headers.
    HeadersMessage headers =
        new HeadersMessage(
            unitTestParams, b2.cloneAsHeader(), b3.cloneAsHeader(), b4.cloneAsHeader());
    // We expect to be asked for b3 and b4 again, but this time, with a body.
    expectedLocator.clear();
    expectedLocator.add(b2.getHash());
    expectedLocator.add(b1.getHash());
    expectedLocator.add(unitTestParams.getGenesisBlock().getHash());
    inbound(writeTarget, headers);
    GetBlocksMessage getblocks = (GetBlocksMessage) outbound(writeTarget);
    assertEquals(expectedLocator, getblocks.getLocator());
    assertEquals(Sha256Hash.ZERO_HASH, getblocks.getStopHash());
    // We're supposed to get an inv here.
    InventoryMessage inv = new InventoryMessage(unitTestParams);
    inv.addItem(new InventoryItem(InventoryItem.Type.Block, b3.getHash()));
    inbound(writeTarget, inv);
    GetDataMessage getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(b3.getHash(), getdata.getItems().get(0).hash);
    // All done.
    inbound(writeTarget, b3);
    pingAndWait(writeTarget);
    closePeer(peer);
  }
 @Test
 public void fourPeers() throws Exception {
   InboundMessageQueuer[] channels = {
     connectPeer(1), connectPeer(2), connectPeer(3), connectPeer(4)
   };
   Transaction tx = new Transaction(params);
   TransactionBroadcast broadcast = new TransactionBroadcast(peerGroup, tx);
   ListenableFuture<Transaction> future = broadcast.broadcast();
   assertFalse(future.isDone());
   // We expect two peers to receive a tx message, and at least one of the others must announce for
   // the future to
   // complete successfully.
   Message[] messages = {
     (Message) outbound(channels[0]),
     (Message) outbound(channels[1]),
     (Message) outbound(channels[2]),
     (Message) outbound(channels[3])
   };
   // 0 and 3 are randomly selected to receive the broadcast.
   assertEquals(tx, messages[0]);
   assertEquals(tx, messages[3]);
   assertNull(messages[1]);
   assertNull(messages[2]);
   Threading.waitForUserCode();
   assertFalse(future.isDone());
   inbound(channels[1], InventoryMessage.with(tx));
   pingAndWait(channels[1]);
   Threading.waitForUserCode();
   assertTrue(future.isDone());
 }
Example #5
0
  // Check that an inv to a peer that is not set to download missing blocks does nothing.
  @Test
  public void invNoDownload() throws Exception {
    // Don't download missing blocks.
    peer.setDownloadData(false);

    connect();

    // Make a missing block that we receive.
    Block b1 = createFakeBlock(blockStore).block;
    blockChain.add(b1);
    Block b2 = makeSolvedTestBlock(b1);

    // Receive an inv.
    InventoryMessage inv = new InventoryMessage(unitTestParams);
    InventoryItem item = new InventoryItem(InventoryItem.Type.Block, b2.getHash());
    inv.addItem(item);
    inbound(writeTarget, inv);

    // Peer does nothing with it.
    assertNull(outbound(writeTarget));
  }
Example #6
0
  @Test
  public void invDownloadTx() throws Exception {
    connect();

    peer.setDownloadData(true);
    // Make a transaction and tell the peer we have it.
    BigInteger value = Utils.toNanoCoins(1, 0);
    Transaction tx = createFakeTx(unitTestParams, value, address);
    InventoryMessage inv = new InventoryMessage(unitTestParams);
    InventoryItem item = new InventoryItem(InventoryItem.Type.Transaction, tx.getHash());
    inv.addItem(item);
    inbound(writeTarget, inv);
    // Peer hasn't seen it before, so will ask for it.
    GetDataMessage getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(1, getdata.getItems().size());
    assertEquals(tx.getHash(), getdata.getItems().get(0).hash);
    inbound(writeTarget, tx);
    // Ask for the dependency, it's not in the mempool (in chain).
    getdata = (GetDataMessage) outbound(writeTarget);
    inbound(writeTarget, new NotFoundMessage(unitTestParams, getdata.getItems()));
    pingAndWait(writeTarget);
    assertEquals(value, wallet.getBalance(Wallet.BalanceType.ESTIMATED));
  }
Example #7
0
  // Check that an inventory tickle is processed correctly when downloading missing blocks is
  // active.
  @Test
  public void invTickle() throws Exception {
    connect();

    Block b1 = createFakeBlock(blockStore).block;
    blockChain.add(b1);
    // Make a missing block.
    Block b2 = makeSolvedTestBlock(b1);
    Block b3 = makeSolvedTestBlock(b2);
    inbound(writeTarget, b3);
    InventoryMessage inv = new InventoryMessage(unitTestParams);
    InventoryItem item = new InventoryItem(InventoryItem.Type.Block, b3.getHash());
    inv.addItem(item);
    inbound(writeTarget, inv);

    GetBlocksMessage getblocks = (GetBlocksMessage) outbound(writeTarget);
    List<Sha256Hash> expectedLocator = new ArrayList<Sha256Hash>();
    expectedLocator.add(b1.getHash());
    expectedLocator.add(unitTestParams.getGenesisBlock().getHash());

    assertEquals(getblocks.getLocator(), expectedLocator);
    assertEquals(getblocks.getStopHash(), b3.getHash());
    assertNull(outbound(writeTarget));
  }
  @Test
  public void peerGroupWalletIntegration() throws Exception {
    // Make sure we can create spends, and that they are announced. Then do the same with offline
    // mode.

    // Set up connections and block chain.
    VersionMessage ver = new VersionMessage(params, 2);
    ver.localServices = VersionMessage.NODE_NETWORK;
    InboundMessageQueuer p1 = connectPeer(1, ver);
    InboundMessageQueuer p2 = connectPeer(2);

    // Send ourselves a bit of money.
    Block b1 = TestUtils.makeSolvedTestBlock(blockStore, address);
    inbound(p1, b1);
    pingAndWait(p1);
    assertNull(outbound(p1));
    assertEquals(Utils.toNanoCoins(50, 0), wallet.getBalance());

    // Check that the wallet informs us of changes in confidence as the transaction ripples across
    // the network.
    final Transaction[] transactions = new Transaction[1];
    wallet.addEventListener(
        new AbstractWalletEventListener() {
          @Override
          public void onTransactionConfidenceChanged(Wallet wallet, Transaction tx) {
            transactions[0] = tx;
          }
        });

    // Now create a spend, and expect the announcement on p1.
    Address dest = new ECKey().toAddress(params);
    Wallet.SendResult sendResult = wallet.sendCoins(peerGroup, dest, Utils.toNanoCoins(1, 0));
    assertNotNull(sendResult.tx);
    Threading.waitForUserCode();
    assertFalse(sendResult.broadcastComplete.isDone());
    assertEquals(transactions[0], sendResult.tx);
    assertEquals(0, transactions[0].getConfidence().numBroadcastPeers());
    transactions[0] = null;
    Transaction t1 = (Transaction) outbound(p1);
    assertNotNull(t1);
    // 49 BTC in change.
    assertEquals(Utils.toNanoCoins(49, 0), t1.getValueSentToMe(wallet));
    // The future won't complete until it's heard back from the network on p2.
    InventoryMessage inv = new InventoryMessage(params);
    inv.addTransaction(t1);
    inbound(p2, inv);
    pingAndWait(p2);
    Threading.waitForUserCode();
    assertTrue(sendResult.broadcastComplete.isDone());
    assertEquals(transactions[0], sendResult.tx);
    assertEquals(1, transactions[0].getConfidence().numBroadcastPeers());
    // Confirm it.
    Block b2 = TestUtils.createFakeBlock(blockStore, t1).block;
    inbound(p1, b2);
    pingAndWait(p1);
    assertNull(outbound(p1));

    // Do the same thing with an offline transaction.
    peerGroup.removeWallet(wallet);
    Wallet.SendRequest req = Wallet.SendRequest.to(dest, Utils.toNanoCoins(2, 0));
    req.ensureMinRequiredFee = false;
    Transaction t3 = checkNotNull(wallet.sendCoinsOffline(req));
    assertNull(outbound(p1)); // Nothing sent.
    // Add the wallet to the peer group (simulate initialization). Transactions should be announced.
    peerGroup.addWallet(wallet);
    // Transaction announced to the first peer.
    assertEquals(t3.getHash(), ((Transaction) outbound(p1)).getHash());
  }
Example #9
0
 private void checkTimeLockedDependency(boolean shouldAccept, boolean useNotFound)
     throws Exception {
   // Initial setup.
   connectWithVersion(useNotFound ? 70001 : 60001);
   ECKey key = new ECKey();
   Wallet wallet = new Wallet(unitTestParams);
   wallet.addKey(key);
   wallet.setAcceptRiskyTransactions(shouldAccept);
   peer.addWallet(wallet);
   final Transaction[] vtx = new Transaction[1];
   wallet.addEventListener(
       new AbstractWalletEventListener() {
         @Override
         public void onCoinsReceived(
             Wallet wallet, Transaction tx, BigInteger prevBalance, BigInteger newBalance) {
           vtx[0] = tx;
         }
       });
   // t1 -> t2 [locked] -> t3 (not available)
   Transaction t2 = new Transaction(unitTestParams);
   t2.setLockTime(999999);
   // Add a fake input to t3 that goes nowhere.
   Sha256Hash t3 = Sha256Hash.create("abc".getBytes(Charset.forName("UTF-8")));
   t2.addInput(
       new TransactionInput(
           unitTestParams, t2, new byte[] {}, new TransactionOutPoint(unitTestParams, 0, t3)));
   t2.getInput(0).setSequenceNumber(0xDEADBEEF);
   t2.addOutput(Utils.toNanoCoins(1, 0), new ECKey());
   Transaction t1 = new Transaction(unitTestParams);
   t1.addInput(t2.getOutput(0));
   t1.addOutput(Utils.toNanoCoins(1, 0), key); // Make it relevant.
   // Announce t1.
   InventoryMessage inv = new InventoryMessage(unitTestParams);
   inv.addTransaction(t1);
   inbound(writeTarget, inv);
   // Send it.
   GetDataMessage getdata = (GetDataMessage) outbound(writeTarget);
   assertEquals(t1.getHash(), getdata.getItems().get(0).hash);
   inbound(writeTarget, t1);
   // Nothing arrived at our event listener yet.
   assertNull(vtx[0]);
   // We request t2.
   getdata = (GetDataMessage) outbound(writeTarget);
   assertEquals(t2.getHash(), getdata.getItems().get(0).hash);
   inbound(writeTarget, t2);
   if (!useNotFound) bouncePing();
   // We request t3.
   getdata = (GetDataMessage) outbound(writeTarget);
   assertEquals(t3, getdata.getItems().get(0).hash);
   // Can't find it: bottom of tree.
   if (useNotFound) {
     NotFoundMessage notFound = new NotFoundMessage(unitTestParams);
     notFound.addItem(new InventoryItem(InventoryItem.Type.Transaction, t3));
     inbound(writeTarget, notFound);
   } else {
     bouncePing();
   }
   pingAndWait(writeTarget);
   Threading.waitForUserCode();
   // We're done but still not notified because it was timelocked.
   if (shouldAccept) assertNotNull(vtx[0]);
   else assertNull(vtx[0]);
 }
Example #10
0
  public void recursiveDownload(boolean useNotFound) throws Exception {
    // Using ping or notfound?
    connectWithVersion(useNotFound ? 70001 : 60001);
    // Check that we can download all dependencies of an unconfirmed relevant transaction from the
    // mempool.
    ECKey to = new ECKey();

    final Transaction[] onTx = new Transaction[1];
    peer.addEventListener(
        new AbstractPeerEventListener() {
          @Override
          public void onTransaction(Peer peer1, Transaction t) {
            onTx[0] = t;
          }
        },
        Threading.SAME_THREAD);

    // Make the some fake transactions in the following graph:
    //   t1 -> t2 -> [t5]
    //      -> t3 -> t4 -> [t6]
    //      -> [t7]
    //      -> [t8]
    // The ones in brackets are assumed to be in the chain and are represented only by hashes.
    Transaction t2 = TestUtils.createFakeTx(unitTestParams, Utils.toNanoCoins(1, 0), to);
    Sha256Hash t5 = t2.getInput(0).getOutpoint().getHash();
    Transaction t4 = TestUtils.createFakeTx(unitTestParams, Utils.toNanoCoins(1, 0), new ECKey());
    Sha256Hash t6 = t4.getInput(0).getOutpoint().getHash();
    t4.addOutput(Utils.toNanoCoins(1, 0), new ECKey());
    Transaction t3 = new Transaction(unitTestParams);
    t3.addInput(t4.getOutput(0));
    t3.addOutput(Utils.toNanoCoins(1, 0), new ECKey());
    Transaction t1 = new Transaction(unitTestParams);
    t1.addInput(t2.getOutput(0));
    t1.addInput(t3.getOutput(0));
    Sha256Hash someHash =
        new Sha256Hash("2b801dd82f01d17bbde881687bf72bc62e2faa8ab8133d36fcb8c3abe7459da6");
    t1.addInput(
        new TransactionInput(
            unitTestParams,
            t1,
            new byte[] {},
            new TransactionOutPoint(unitTestParams, 0, someHash)));
    Sha256Hash anotherHash =
        new Sha256Hash("3b801dd82f01d17bbde881687bf72bc62e2faa8ab8133d36fcb8c3abe7459da6");
    t1.addInput(
        new TransactionInput(
            unitTestParams,
            t1,
            new byte[] {},
            new TransactionOutPoint(unitTestParams, 1, anotherHash)));
    t1.addOutput(Utils.toNanoCoins(1, 0), to);
    t1 = TestUtils.roundTripTransaction(unitTestParams, t1);
    t2 = TestUtils.roundTripTransaction(unitTestParams, t2);
    t3 = TestUtils.roundTripTransaction(unitTestParams, t3);
    t4 = TestUtils.roundTripTransaction(unitTestParams, t4);

    // Announce the first one. Wait for it to be downloaded.
    InventoryMessage inv = new InventoryMessage(unitTestParams);
    inv.addTransaction(t1);
    inbound(writeTarget, inv);
    GetDataMessage getdata = (GetDataMessage) outbound(writeTarget);
    Threading.waitForUserCode();
    assertEquals(t1.getHash(), getdata.getItems().get(0).hash);
    inbound(writeTarget, t1);
    pingAndWait(writeTarget);
    assertEquals(t1, onTx[0]);
    // We want its dependencies so ask for them.
    ListenableFuture<List<Transaction>> futures = peer.downloadDependencies(t1);
    assertFalse(futures.isDone());
    // It will recursively ask for the dependencies of t1: t2, t3, someHash and anotherHash.
    getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(4, getdata.getItems().size());
    assertEquals(t2.getHash(), getdata.getItems().get(0).hash);
    assertEquals(t3.getHash(), getdata.getItems().get(1).hash);
    assertEquals(someHash, getdata.getItems().get(2).hash);
    assertEquals(anotherHash, getdata.getItems().get(3).hash);
    long nonce = -1;
    if (!useNotFound) nonce = ((Ping) outbound(writeTarget)).getNonce();
    // For some random reason, t4 is delivered at this point before it's needed - perhaps it was a
    // Bloom filter
    // false positive. We do this to check that the mempool is being checked for seen transactions
    // before
    // requesting them.
    inbound(writeTarget, t4);
    // Deliver the requested transactions.
    inbound(writeTarget, t2);
    inbound(writeTarget, t3);
    if (useNotFound) {
      NotFoundMessage notFound = new NotFoundMessage(unitTestParams);
      notFound.addItem(new InventoryItem(InventoryItem.Type.Transaction, someHash));
      notFound.addItem(new InventoryItem(InventoryItem.Type.Transaction, anotherHash));
      inbound(writeTarget, notFound);
    } else {
      inbound(writeTarget, new Pong(nonce));
    }
    assertFalse(futures.isDone());
    // It will recursively ask for the dependencies of t2: t5 and t4, but not t3 because it already
    // found t4.
    getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(getdata.getItems().get(0).hash, t2.getInput(0).getOutpoint().getHash());
    // t5 isn't found and t4 is.
    if (useNotFound) {
      NotFoundMessage notFound = new NotFoundMessage(unitTestParams);
      notFound.addItem(new InventoryItem(InventoryItem.Type.Transaction, t5));
      inbound(writeTarget, notFound);
    } else {
      bouncePing();
    }
    assertFalse(futures.isDone());
    // Continue to explore the t4 branch and ask for t6, which is in the chain.
    getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(t6, getdata.getItems().get(0).hash);
    if (useNotFound) {
      NotFoundMessage notFound = new NotFoundMessage(unitTestParams);
      notFound.addItem(new InventoryItem(InventoryItem.Type.Transaction, t6));
      inbound(writeTarget, notFound);
    } else {
      bouncePing();
    }
    pingAndWait(writeTarget);
    // That's it, we explored the entire tree.
    assertTrue(futures.isDone());
    List<Transaction> results = futures.get();
    assertTrue(results.contains(t2));
    assertTrue(results.contains(t3));
    assertTrue(results.contains(t4));
  }
Example #11
0
  @Test
  public void chainDownloadEnd2End() throws Exception {
    // A full end-to-end test of the chain download process, with a new block being solved in the
    // middle.
    Block b1 = createFakeBlock(blockStore).block;
    blockChain.add(b1);
    Block b2 = makeSolvedTestBlock(b1);
    Block b3 = makeSolvedTestBlock(b2);
    Block b4 = makeSolvedTestBlock(b3);
    Block b5 = makeSolvedTestBlock(b4);

    connect();

    peer.startBlockChainDownload();
    GetBlocksMessage getblocks = (GetBlocksMessage) outbound(writeTarget);
    assertEquals(blockStore.getChainHead().getHeader().getHash(), getblocks.getLocator().get(0));
    assertEquals(Sha256Hash.ZERO_HASH, getblocks.getStopHash());
    // Remote peer sends us an inv with some blocks.
    InventoryMessage inv = new InventoryMessage(unitTestParams);
    inv.addBlock(b2);
    inv.addBlock(b3);
    // We do a getdata on them.
    inbound(writeTarget, inv);
    GetDataMessage getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(b2.getHash(), getdata.getItems().get(0).hash);
    assertEquals(b3.getHash(), getdata.getItems().get(1).hash);
    assertEquals(2, getdata.getItems().size());
    // Remote peer sends us the blocks. The act of doing a getdata for b3 results in getting an inv
    // with just the
    // best chain head in it.
    inbound(writeTarget, b2);
    inbound(writeTarget, b3);

    inv = new InventoryMessage(unitTestParams);
    inv.addBlock(b5);
    // We request the head block.
    inbound(writeTarget, inv);
    getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(b5.getHash(), getdata.getItems().get(0).hash);
    assertEquals(1, getdata.getItems().size());
    // Peer sends us the head block. The act of receiving the orphan block triggers a getblocks to
    // fill in the
    // rest of the chain.
    inbound(writeTarget, b5);
    getblocks = (GetBlocksMessage) outbound(writeTarget);
    assertEquals(b5.getHash(), getblocks.getStopHash());
    assertEquals(b3.getHash(), getblocks.getLocator().get(0));
    // At this point another block is solved and broadcast. The inv triggers a getdata but we do NOT
    // send another
    // getblocks afterwards, because that would result in us receiving the same set of blocks twice
    // which is a
    // timewaste. The getblocks message that would have been generated is set to be the same as the
    // previous
    // because we walk backwards down the orphan chain and then discover we already asked for those
    // blocks, so
    // nothing is done.
    Block b6 = makeSolvedTestBlock(b5);
    inv = new InventoryMessage(unitTestParams);
    inv.addBlock(b6);
    inbound(writeTarget, inv);
    getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(1, getdata.getItems().size());
    assertEquals(b6.getHash(), getdata.getItems().get(0).hash);
    inbound(writeTarget, b6);
    assertNull(outbound(writeTarget)); // Nothing is sent at this point.
    // We're still waiting for the response to the getblocks (b3,b5) sent above.
    inv = new InventoryMessage(unitTestParams);
    inv.addBlock(b4);
    inv.addBlock(b5);
    inbound(writeTarget, inv);
    getdata = (GetDataMessage) outbound(writeTarget);
    assertEquals(1, getdata.getItems().size());
    assertEquals(b4.getHash(), getdata.getItems().get(0).hash);
    // We already have b5 from before, so it's not requested again.
    inbound(writeTarget, b4);
    assertNull(outbound(writeTarget));
    // b5 and b6 are now connected by the block chain and we're done.
    assertNull(outbound(writeTarget));
    closePeer(peer);
  }