Enforce block version supermajority for BIP 66 onwards.

core/src/main/java/org/bitcoinj/core/AbstractBlockChain.java

@@ -35,6 +35,7 @@
 import java.util.concurrent.locks.ReentrantLock;
 
 import static com.google.common.base.Preconditions.*;
+import org.bitcoinj.utils.VersionTally;
 
 /**
  * <p>An AbstractBlockChain holds a series of {@link Block} objects, links them together, and knows how to verify that
@@ -136,6 +137,8 @@ class OrphanBlock {
     private double falsePositiveTrend;
     private double previousFalsePositiveRate;
 
+    private final VersionTally versionTally;
+
     /** See {@link #AbstractBlockChain(Context, List, BlockStore)} */
     public AbstractBlockChain(NetworkParameters params, List<BlockChainListener> listeners,
                               BlockStore blockStore) throws BlockStoreException {
@@ -153,6 +156,8 @@ public AbstractBlockChain(Context context, List<BlockChainListener> listeners,
         this.params = context.getParams();
         this.listeners = new CopyOnWriteArrayList<ListenerRegistration<BlockChainListener>>();
         for (BlockChainListener l : listeners) addListener(l, Threading.SAME_THREAD);
+        this.versionTally = new VersionTally(context.getParams());
+        this.versionTally.initialize(blockStore, chainHead);
     }
 
     /**
@@ -458,13 +463,26 @@ private void connectBlock(final Block block, StoredBlock storedPrev, boolean exp
             }
             if (expensiveChecks && block.getTimeSeconds() <= getMedianTimestampOfRecentBlocks(head, blockStore))
                 throw new VerificationException("Block's timestamp is too early");
-
+
+            // BIP 66: Enforce block version 3 once it's a supermajority of blocks
+            // NOTE: This requires 1,000 blocks since the last checkpoint (on main
+            // net, less on test) in order to be applied. It is also limited to
+            // stopping addition of new v2 blocks to the tip of the chain.
+            if (block.getVersion() == Block.BLOCK_VERSION_BIP34) {
+                final Integer count = versionTally.getCount(Block.BLOCK_VERSION_BIP66);
+                if (count != null
+                    && count >= params.getMajorityRejectBlockOutdated()) {
+                    throw new VerificationException.BlockVersionOutOfDate(block.getVersion());
+                }
+            }
+
             // This block connects to the best known block, it is a normal continuation of the system.
             TransactionOutputChanges txOutChanges = null;
             if (shouldVerifyTransactions())
                 txOutChanges = connectTransactions(storedPrev.getHeight() + 1, block);
             StoredBlock newStoredBlock = addToBlockStore(storedPrev,
                     block.transactions == null ? block : block.cloneAsHeader(), txOutChanges);
+            versionTally.add(block.getVersion());
             setChainHead(newStoredBlock);
             log.debug("Chain is now {} blocks high, running listeners", newStoredBlock.getHeight());
             informListenersForNewBlock(block, NewBlockType.BEST_CHAIN, filteredTxHashList, filteredTxn, newStoredBlock);

core/src/main/java/org/bitcoinj/core/Block.java

@@ -72,6 +72,12 @@ public class Block extends Message {
     /** A value for difficultyTarget (nBits) that allows half of all possible hash solutions. Used in unit testing. */
     public static final long EASIEST_DIFFICULTY_TARGET = 0x207fFFFFL;
 
+    public static final long BLOCK_VERSION_GENESIS = 1;
+    /** Block version introduced in BIP 34: Height in coinbase */
+    public static final long BLOCK_VERSION_BIP34 = 2;
+    /** Block version introduced in BIP 66: Strict DER signatures */
+    public static final long BLOCK_VERSION_BIP66 = 3;
+
     // Fields defined as part of the protocol format.
     private long version;
     private Sha256Hash prevBlockHash;
@@ -99,10 +105,10 @@ public class Block extends Message {
     protected int optimalEncodingMessageSize;
 
     /** Special case constructor, used for the genesis node, cloneAsHeader and unit tests. */
-    Block(NetworkParameters params) {
+    Block(NetworkParameters params, long setVersion) {
         super(params);
         // Set up a few basic things. We are not complete after this though.
-        version = 1;
+        version = setVersion;
         difficultyTarget = 0x1d07fff8L;
         time = System.currentTimeMillis() / 1000;
         prevBlockHash = Sha256Hash.ZERO_HASH;
@@ -579,7 +585,7 @@ public BigInteger getWork() throws VerificationException {
     /** Returns a copy of the block, but without any transactions. */
     public Block cloneAsHeader() {
         maybeParseHeader();
-        Block block = new Block(params);
+        Block block = new Block(params, BLOCK_VERSION_GENESIS);
         copyBitcoinHeaderTo(block);
         return block;
     }
@@ -1002,17 +1008,17 @@ void addCoinbaseTransaction(byte[] pubKeyTo, Coin value) {
      * Returns a solved block that builds on top of this one. This exists for unit tests.
      */
     @VisibleForTesting
-    public Block createNextBlock(Address to, long time) {
-        return createNextBlock(to, null, time, pubkeyForTesting, FIFTY_COINS);
+    public Block createNextBlock(Address to, long version, long time) {
+        return createNextBlock(to, version, null, time, pubkeyForTesting, FIFTY_COINS);
     }
 
     /**
      * Returns a solved block that builds on top of this one. This exists for unit tests.
      * In this variant you can specify a public key (pubkey) for use in generating coinbase blocks.
      */
-    Block createNextBlock(@Nullable Address to, @Nullable TransactionOutPoint prevOut, long time,
-                          byte[] pubKey, Coin coinbaseValue) {
-        Block b = new Block(params);
+    Block createNextBlock(@Nullable Address to, long version, @Nullable TransactionOutPoint prevOut,
+                          long time, byte[] pubKey, Coin coinbaseValue) {
+        Block b = new Block(params, version);
         b.setDifficultyTarget(difficultyTarget);
         b.addCoinbaseTransaction(pubKey, coinbaseValue);
 
@@ -1054,12 +1060,12 @@ Block createNextBlock(@Nullable Address to, @Nullable TransactionOutPoint prevOu
 
     @VisibleForTesting
     public Block createNextBlock(@Nullable Address to, TransactionOutPoint prevOut) {
-        return createNextBlock(to, prevOut, getTimeSeconds() + 5, pubkeyForTesting, FIFTY_COINS);
+        return createNextBlock(to, 1, prevOut, getTimeSeconds() + 5, pubkeyForTesting, FIFTY_COINS);
     }
 
     @VisibleForTesting
     public Block createNextBlock(@Nullable Address to, Coin value) {
-        return createNextBlock(to, null, getTimeSeconds() + 5, pubkeyForTesting, value);
+        return createNextBlock(to, 1, null, getTimeSeconds() + 5, pubkeyForTesting, value);
     }
 
     @VisibleForTesting
@@ -1069,7 +1075,7 @@ public Block createNextBlock(@Nullable Address to) {
 
     @VisibleForTesting
     public Block createNextBlockWithCoinbase(byte[] pubKey, Coin coinbaseValue) {
-        return createNextBlock(null, null, Utils.currentTimeSeconds(), pubKey, coinbaseValue);
+        return createNextBlock(null, 1, null, Utils.currentTimeSeconds(), pubKey, coinbaseValue);
     }
 
     /**
@@ -1078,7 +1084,7 @@ public Block createNextBlockWithCoinbase(byte[] pubKey, Coin coinbaseValue) {
      */
     @VisibleForTesting
     Block createNextBlockWithCoinbase(byte[] pubKey) {
-        return createNextBlock(null, null, Utils.currentTimeSeconds(), pubKey, FIFTY_COINS);
+        return createNextBlock(null, 1, null, Utils.currentTimeSeconds(), pubKey, FIFTY_COINS);
     }
 
     @VisibleForTesting

core/src/main/java/org/bitcoinj/core/NetworkParameters.java

@@ -87,6 +87,11 @@ public abstract class NetworkParameters {
     protected int bip32HeaderPub;
     protected int bip32HeaderPriv;
 
+    /** Used to check majorities for block version upgrade */
+    protected int majorityEnforceBlockUpgrade;
+    protected int majorityRejectBlockOutdated;
+    protected int majorityWindow;
+
     /**
      * See getId(). This may be null for old deserialized wallets. In that case we derive it heuristically
      * by looking at the port number.
@@ -112,7 +117,7 @@ protected NetworkParameters() {
     }
 
     private static Block createGenesis(NetworkParameters n) {
-        Block genesisBlock = new Block(n);
+        Block genesisBlock = new Block(n, Block.BLOCK_VERSION_GENESIS);
         Transaction t = new Transaction(n);
         try {
             // A script containing the difficulty bits and the following message:
@@ -445,4 +450,30 @@ public final MessageSerializer getDefaultSerializer() {
      * Construct and return a custom serializer.
      */
     public abstract BitcoinSerializer getSerializer(boolean parseLazy, boolean parseRetain);
+
+    /**
+     * The number of blocks in the last {@link getMajorityWindow()} blocks
+     * at which to trigger a notice to the user to upgrade their client, where
+     * the client does not understand those blocks.
+     */
+    public int getMajorityEnforceBlockUpgrade() {
+        return majorityEnforceBlockUpgrade;
+    }
+
+    /**
+     * The number of blocks in the last {@link getMajorityWindow()} blocks
+     * at which to enforce the requirement that all new blocks are of the
+     * newer type (i.e. outdated blocks are rejected).
+     */
+    public int getMajorityRejectBlockOutdated() {
+        return majorityRejectBlockOutdated;
+    }
+
+    /**
+     * The sampling window from which the version numbers of blocks are taken
+     * in order to determine if a new block version is now the majority.
+     */
+    public int getMajorityWindow() {
+        return majorityWindow;
+    }
 }

core/src/main/java/org/bitcoinj/core/VerificationException.java

@@ -42,7 +42,6 @@ public LargerThanMaxBlockSize() {
         }
     }
 
-
     public static class DuplicatedOutPoint extends VerificationException {
         public DuplicatedOutPoint() {
             super("Duplicated outpoint");
@@ -68,6 +67,14 @@ public CoinbaseScriptSizeOutOfRange() {
         }
     }
 
+
+    public static class BlockVersionOutOfDate extends VerificationException {
+        public BlockVersionOutOfDate(final long version) {
+            super("Block version #"
+                + version + " is outdated.");
+        }
+    }
+
     public static class UnexpectedCoinbaseInput extends VerificationException {
         public UnexpectedCoinbaseInput() {
             super("Coinbase input as input in non-coinbase transaction");

core/src/main/java/org/bitcoinj/params/AbstractBitcoinNetParams.java

@@ -118,7 +118,7 @@ public void checkDifficultyTransitions(final StoredBlock storedPrev, final Block
 
         if (newTargetCompact != receivedTargetCompact)
             throw new VerificationException("Network provided difficulty bits do not match what was calculated: " +
-                    newTargetCompact + " vs " + receivedTargetCompact);
+                    Long.toHexString(newTargetCompact) + " vs " + Long.toHexString(receivedTargetCompact));
     }
 
     @Override

core/src/main/java/org/bitcoinj/params/MainNetParams.java

@@ -28,6 +28,10 @@
  * Parameters for the main production network on which people trade goods and services.
  */
 public class MainNetParams extends AbstractBitcoinNetParams {
+    public static final int MAINNET_MAJORITY_WINDOW = 1000;
+    public static final int MAINNET_MAJORITY_REJECT_BLOCK_OUTDATED = 950;
+    public static final int MAINNET_MAJORITY_ENFORCE_BLOCK_UPGRADE = 750;
+
     public MainNetParams() {
         super();
         interval = INTERVAL;
@@ -42,6 +46,10 @@ public MainNetParams() {
         bip32HeaderPub = 0x0488B21E; //The 4 byte header that serializes in base58 to "xpub".
         bip32HeaderPriv = 0x0488ADE4; //The 4 byte header that serializes in base58 to "xprv"
 
+        majorityEnforceBlockUpgrade = MAINNET_MAJORITY_ENFORCE_BLOCK_UPGRADE;
+        majorityRejectBlockOutdated = MAINNET_MAJORITY_REJECT_BLOCK_OUTDATED;
+        majorityWindow = MAINNET_MAJORITY_WINDOW;
+
         genesisBlock.setDifficultyTarget(0x1d00ffffL);
         genesisBlock.setTime(1231006505L);
         genesisBlock.setNonce(2083236893);

core/src/main/java/org/bitcoinj/params/RegTestParams.java

@@ -35,6 +35,10 @@ public RegTestParams() {
         subsidyDecreaseBlockCount = 150;
         port = 18444;
         id = ID_REGTEST;
+
+        majorityEnforceBlockUpgrade = MainNetParams.MAINNET_MAJORITY_ENFORCE_BLOCK_UPGRADE;
+        majorityRejectBlockOutdated = MainNetParams.MAINNET_MAJORITY_REJECT_BLOCK_OUTDATED;
+        majorityWindow = MainNetParams.MAINNET_MAJORITY_WINDOW;
     }
 
     @Override

core/src/main/java/org/bitcoinj/params/TestNet2Params.java

@@ -25,6 +25,10 @@
  * based on it.
  */
 public class TestNet2Params extends AbstractBitcoinNetParams {
+    public static final int TESTNET_MAJORITY_WINDOW = 100;
+    public static final int TESTNET_MAJORITY_REJECT_BLOCK_OUTDATED = 75;
+    public static final int TESTNET_MAJORITY_ENFORCE_BLOCK_UPGRADE = 51;
+
     public TestNet2Params() {
         super();
         id = ID_TESTNET;
@@ -48,6 +52,10 @@ public TestNet2Params() {
         addrSeeds = null;
         bip32HeaderPub = 0x043587CF;
         bip32HeaderPriv = 0x04358394;
+
+        majorityEnforceBlockUpgrade = TESTNET_MAJORITY_ENFORCE_BLOCK_UPGRADE;
+        majorityRejectBlockOutdated = TESTNET_MAJORITY_REJECT_BLOCK_OUTDATED;
+        majorityWindow = TESTNET_MAJORITY_WINDOW;
     }
 
     private static TestNet2Params instance;

core/src/main/java/org/bitcoinj/params/UnitTestParams.java

@@ -25,6 +25,10 @@
  * {@link org.bitcoinj.core.Block#solve()} by setting difficulty to the easiest possible.
  */
 public class UnitTestParams extends AbstractBitcoinNetParams {
+    public static final int UNITNET_MAJORITY_WINDOW = 8;
+    public static final int TESTNET_MAJORITY_REJECT_BLOCK_OUTDATED = 6;
+    public static final int TESTNET_MAJORITY_ENFORCE_BLOCK_UPGRADE = 4;
+
     // A simple static key/address for re-use in unit tests, to speed things up.
     public static ECKey TEST_KEY = new ECKey();
     public static Address TEST_ADDRESS;
@@ -50,6 +54,10 @@ public UnitTestParams() {
         addrSeeds = null;
         bip32HeaderPub = 0x043587CF;
         bip32HeaderPriv = 0x04358394;
+
+        majorityEnforceBlockUpgrade = 3;
+        majorityRejectBlockOutdated = 4;
+        majorityWindow = 7;
     }
 
     private static UnitTestParams instance;

core/src/main/java/org/bitcoinj/testing/FakeTxBuilder.java

@@ -167,11 +167,12 @@ public static class BlockPair {
     }
 
     /** Emulates receiving a valid block that builds on top of the chain. */
-    public static BlockPair createFakeBlock(BlockStore blockStore, long timeSeconds, Transaction... transactions) {
+    public static BlockPair createFakeBlock(BlockStore blockStore, long version, long timeSeconds,
+                                            Transaction... transactions) {
         try {
             Block chainHead = blockStore.getChainHead().getHeader();
             Address to = new ECKey().toAddress(chainHead.getParams());
-            Block b = chainHead.createNextBlock(to, timeSeconds);
+            Block b = chainHead.createNextBlock(to, version, timeSeconds);
             // Coinbase tx was already added.
             for (Transaction tx : transactions) {
                 tx.getConfidence().setSource(TransactionConfidence.Source.NETWORK);
@@ -191,8 +192,9 @@ public static BlockPair createFakeBlock(BlockStore blockStore, long timeSeconds,
         }
     }
 
+    /** Emulates receiving a valid block that builds on top of the chain. */
     public static BlockPair createFakeBlock(BlockStore blockStore, Transaction... transactions) {
-        return createFakeBlock(blockStore, Utils.currentTimeSeconds(), transactions);
+        return createFakeBlock(blockStore, Block.BLOCK_VERSION_GENESIS, Utils.currentTimeSeconds(), transactions);
     }
 
     public static Block makeSolvedTestBlock(BlockStore blockStore, Address coinsTo) throws BlockStoreException {