Added tests for subsequent preprepare

consensus/ibft/src/main/java/tech/pegasys/pantheon/consensus/ibft/ibftmessagedata/IbftUnsignedPrePrepareMessageData.java

@@ -19,6 +19,8 @@
 import tech.pegasys.pantheon.ethereum.rlp.RLPInput;
 import tech.pegasys.pantheon.ethereum.rlp.RLPOutput;
 
+import java.util.Objects;
+
 // NOTE: Implementation of all methods of this class is still pending. This class was added to show
 // how a PreparedCertificate is encoded and decoded inside a RoundChange message
 public class IbftUnsignedPrePrepareMessageData extends AbstractIbftUnsignedInRoundMessageData {
@@ -60,4 +62,22 @@ public Block getBlock() {
   public int getMessageType() {
     return TYPE;
   }
+
+  @Override
+  public boolean equals(final Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    IbftUnsignedPrePrepareMessageData that = (IbftUnsignedPrePrepareMessageData) o;
+    return Objects.equals(block, that.block)
+        && Objects.equals(roundIdentifier, that.roundIdentifier);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(block);
+  }
 }

consensus/ibft/src/main/java/tech/pegasys/pantheon/consensus/ibft/validation/MessageValidator.java

@@ -67,6 +67,10 @@ public MessageValidator(
   public boolean addPreprepareMessage(
       final IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> msg) {
 
+    if (preprepareMessage.isPresent()) {
+      return handleSubsequentPreprepareMessage(msg);
+    }
+
     if (!msg.getUnsignedMessageData().getRoundIdentifier().equals(roundIdentifier)) {
       LOG.info("Invalid Preprepare message, does not match current round.");
       return false;
@@ -95,6 +99,26 @@ public boolean addPreprepareMessage(
     return true;
   }
 
+  private boolean handleSubsequentPreprepareMessage(
+      final IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> msg) {
+    IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> existingMsg = preprepareMessage.get();
+
+    if (!existingMsg.getSender().equals(msg.getSender())) {
+      LOG.debug("Received subsequent invalid Preprepare message; sender differs from original.");
+      return false;
+    }
+
+    final IbftUnsignedPrePrepareMessageData existingData = existingMsg.getUnsignedMessageData();
+    final IbftUnsignedPrePrepareMessageData newData = msg.getUnsignedMessageData();
+
+    if (!existingData.equals(newData)) {
+      LOG.debug("Received subsequent invalid Preprepare message; content differs from original.");
+      return false;
+    }
+
+    return true;
+  }
+
   public boolean validatePrepareMessage(
       final IbftSignedMessageData<IbftUnsignedPrepareMessageData> msg) {
     final String msgType = "Prepare";

consensus/ibft/src/test/java/tech/pegasys/pantheon/consensus/ibft/validation/MessageValidatorTest.java

@@ -231,4 +231,44 @@ public void commitMessageContainingValidSealFromValidatorIsSuccessful() {
     assertThat(validator.validateCommmitMessage(proposerCommitMsg)).isTrue();
     assertThat(validator.validateCommmitMessage(validatorCommitMsg)).isTrue();
   }
+
+  @Test
+  public void subsequentPreprepareHasDifferentSenderFails() {
+    when(headerValidator.validateHeader(any(), any(), any(), any())).thenReturn(true);
+
+    final IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> preprepareMsg =
+        proposerMessageFactory.createIbftSignedPrePrepareMessageData(roundIdentifier, block);
+    assertThat(validator.addPreprepareMessage(preprepareMsg)).isTrue();
+
+    final IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> secondPreprepareMsg =
+        validatorMessageFactory.createIbftSignedPrePrepareMessageData(roundIdentifier, block);
+    assertThat(validator.addPreprepareMessage(secondPreprepareMsg)).isFalse();
+  }
+
+  @Test
+  public void subsequentPreprepareHasDifferentContentFails() {
+    when(headerValidator.validateHeader(any(), any(), any(), any())).thenReturn(true);
+
+    final IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> preprepareMsg =
+        proposerMessageFactory.createIbftSignedPrePrepareMessageData(roundIdentifier, block);
+    assertThat(validator.addPreprepareMessage(preprepareMsg)).isTrue();
+
+    final ConsensusRoundIdentifier newRoundIdentifier = new ConsensusRoundIdentifier(3, 0);
+    final IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> secondPreprepareMsg =
+        proposerMessageFactory.createIbftSignedPrePrepareMessageData(newRoundIdentifier, block);
+    assertThat(validator.addPreprepareMessage(secondPreprepareMsg)).isFalse();
+  }
+
+  @Test
+  public void subsequentPreprepareHasIdenticalSenderAndContentIsSuccessful() {
+    when(headerValidator.validateHeader(any(), any(), any(), any())).thenReturn(true);
+
+    final IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> preprepareMsg =
+        proposerMessageFactory.createIbftSignedPrePrepareMessageData(roundIdentifier, block);
+    assertThat(validator.addPreprepareMessage(preprepareMsg)).isTrue();
+
+    final IbftSignedMessageData<IbftUnsignedPrePrepareMessageData> secondPreprepareMsg =
+        proposerMessageFactory.createIbftSignedPrePrepareMessageData(roundIdentifier, block);
+    assertThat(validator.addPreprepareMessage(secondPreprepareMsg)).isTrue();
+  }
 }