Basic support for version 2 transactions.

Rather than considering all version 2 transactions risky, we now look more closely if any of its
inputs has a relative lock time. We can't check the relative locks though, because we usually
don't have the spent outputs (to know when they were creted).

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

@@ -659,6 +659,9 @@ public String toString(@Nullable AbstractBlockChain chain) {
             }
             s.append('\n');
         }
+        if (hasRelativeLockTime()) {
+            s.append("  has relative lock time\n");
+        }
         if (isOptInFullRBF()) {
             s.append("  opts into full replace-by-fee\n");
         }
@@ -702,6 +705,8 @@ public String toString(@Nullable AbstractBlockChain chain) {
                         s.append("\n          sequence:").append(Long.toHexString(in.getSequenceNumber()));
                         if (in.isOptInFullRBF())
                             s.append(", opts into full RBF");
+                        if (version >=2 && in.hasRelativeLockTime())
+                            s.append(", has RLT");
                     }
                 } catch (Exception e) {
                     s.append("[exception: ").append(e.getMessage()).append("]");
@@ -1287,7 +1292,8 @@ public void verify() throws VerificationException {
     }
 
     /**
-     * <p>A transaction is time locked if at least one of its inputs is non-final and it has a lock time</p>
+     * <p>A transaction is time-locked if at least one of its inputs is non-final and it has a lock time. A transaction can
+     * also have a relative lock time which this method doesn't tell. Use {@link #hasRelativeLockTime()} to find out.</p>
      *
      * <p>To check if this transaction is final at a given height and time, see {@link Transaction#isFinal(int, long)}
      * </p>
@@ -1301,6 +1307,20 @@ public boolean isTimeLocked() {
         return false;
     }
 
+    /**
+     * A transaction has a relative lock time
+     * (<a href="https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki">BIP 68</a>) if it is version 2 or
+     * higher and at least one of its inputs has its {@link TransactionInput.SEQUENCE_LOCKTIME_DISABLE_FLAG} cleared.
+     */
+    public boolean hasRelativeLockTime() {
+        if (version < 2)
+            return false;
+        for (TransactionInput input : getInputs())
+            if (input.hasRelativeLockTime())
+                return true;
+        return false;
+    }
+
     /**
      * Returns whether this transaction will opt into the
      * <a href="https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki">full replace-by-fee </a> semantics.

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

@@ -46,6 +46,11 @@
 public class TransactionInput extends ChildMessage {
     /** Magic sequence number that indicates there is no sequence number. */
     public static final long NO_SEQUENCE = 0xFFFFFFFFL;
+    /**
+     * BIP68: If this flag set, sequence is NOT interpreted as a relative lock-time.
+     */
+    public static final long SEQUENCE_LOCKTIME_DISABLE_FLAG = 1L << 31;
+
     private static final byte[] EMPTY_ARRAY = new byte[0];
     // Magic outpoint index that indicates the input is in fact unconnected.
     private static final long UNCONNECTED = 0xFFFFFFFFL;
@@ -385,6 +390,14 @@ public boolean isOptInFullRBF() {
         return sequence < NO_SEQUENCE - 1;
     }
 
+    /**
+     * Returns whether this input, if it belongs to a version 2 (or higher) transaction, has
+     * <a href="https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki">relative lock-time</a> enabled.
+     */
+    public boolean hasRelativeLockTime() {
+        return (sequence & SEQUENCE_LOCKTIME_DISABLE_FLAG) == 0;
+    }
+
     /**
      * For a connected transaction, runs the script against the connected pubkey and verifies they are correct.
      * @throws ScriptException if the script did not verify.

core/src/main/java/org/bitcoinj/wallet/DefaultRiskAnalysis.java

@@ -89,6 +89,13 @@ private Result analyzeIsFinal() {
             return Result.NON_FINAL;
         }
 
+        // Relative time-locked transactions are risky too. We can't check the locks because usually we don't know the
+        // spent outputs (to know when they were created).
+        if (tx.hasRelativeLockTime()) {
+            nonFinal = tx;
+            return Result.NON_FINAL;
+        }
+
         if (wallet == null)
             return null;
 
@@ -133,7 +140,7 @@ public enum RuleViolation {
      */
     public static RuleViolation isStandard(Transaction tx) {
         // TODO: Finish this function off.
-        if (tx.getVersion() > 1 || tx.getVersion() < 1) {
+        if (tx.getVersion() > 2 || tx.getVersion() < 1) {
             log.warn("TX considered non-standard due to unknown version number {}", tx.getVersion());
             return RuleViolation.VERSION;
         }

core/src/test/java/org/bitcoinj/wallet/DefaultRiskAnalysisTest.java

@@ -28,6 +28,7 @@
 
 import java.util.*;
 
+import static com.google.common.base.Preconditions.checkState;
 import static org.bitcoinj.core.Coin.*;
 import static org.bitcoinj.script.ScriptOpCodes.*;
 import static org.junit.Assert.*;
@@ -231,4 +232,37 @@ public void optInFullRBF() throws Exception {
         assertEquals(RiskAnalysis.Result.NON_FINAL, analysis.analyze());
         assertEquals(tx, analysis.getNonFinal());
     }
+
+    @Test
+    public void relativeLockTime() throws Exception {
+        Transaction tx = FakeTxBuilder.createFakeTx(PARAMS);
+        tx.setVersion(2);
+        checkState(!tx.hasRelativeLockTime());
+
+        tx.getInput(0).setSequenceNumber(TransactionInput.NO_SEQUENCE);
+        DefaultRiskAnalysis analysis = DefaultRiskAnalysis.FACTORY.create(wallet, tx, NO_DEPS);
+        assertEquals(RiskAnalysis.Result.OK, analysis.analyze());
+
+        tx.getInput(0).setSequenceNumber(0);
+        analysis = DefaultRiskAnalysis.FACTORY.create(wallet, tx, NO_DEPS);
+        assertEquals(RiskAnalysis.Result.NON_FINAL, analysis.analyze());
+        assertEquals(tx, analysis.getNonFinal());
+    }
+
+    @Test
+    public void transactionVersions() throws Exception {
+        Transaction tx = FakeTxBuilder.createFakeTx(PARAMS);
+        tx.setVersion(1);
+        DefaultRiskAnalysis analysis = DefaultRiskAnalysis.FACTORY.create(wallet, tx, NO_DEPS);
+        assertEquals(RiskAnalysis.Result.OK, analysis.analyze());
+
+        tx.setVersion(2);
+        analysis = DefaultRiskAnalysis.FACTORY.create(wallet, tx, NO_DEPS);
+        assertEquals(RiskAnalysis.Result.OK, analysis.analyze());
+
+        tx.setVersion(3);
+        analysis = DefaultRiskAnalysis.FACTORY.create(wallet, tx, NO_DEPS);
+        assertEquals(RiskAnalysis.Result.NON_STANDARD, analysis.analyze());
+        assertEquals(tx, analysis.getNonStandard());
+    }
 }