Remove RLPUtils from ProofOfWorkValidationRule (#83)

Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

ethereum/core/src/main/java/tech/pegasys/pantheon/ethereum/core/BlockHeaderBuilder.java

@@ -63,6 +63,25 @@ public class BlockHeaderBuilder {
     return new BlockHeaderBuilder();
   }
 
+  public static BlockHeaderBuilder fromHeader(final BlockHeader header) {
+    return create()
+        .parentHash(header.getParentHash())
+        .ommersHash(header.getOmmersHash())
+        .coinbase(header.getCoinbase())
+        .stateRoot(header.getStateRoot())
+        .transactionsRoot(header.getTransactionsRoot())
+        .receiptsRoot(header.getReceiptsRoot())
+        .logsBloom(header.getLogsBloom())
+        .difficulty(header.getDifficulty())
+        .number(header.getNumber())
+        .gasLimit(header.getGasLimit())
+        .gasUsed(header.getGasUsed())
+        .timestamp(header.getTimestamp())
+        .extraData(header.getExtraData())
+        .mixHash(header.getMixHash())
+        .nonce(header.getNonce());
+  }
+
   public BlockHeader buildBlockHeader() {
     validateBlockHeader();
 

ethereum/core/src/main/java/tech/pegasys/pantheon/ethereum/mainnet/headervalidationrules/ProofOfWorkValidationRule.java

@@ -12,64 +12,34 @@
  */
 package tech.pegasys.pantheon.ethereum.mainnet.headervalidationrules;
 
-import tech.pegasys.pantheon.crypto.BouncyCastleMessageDigestFactory;
 import tech.pegasys.pantheon.ethereum.core.BlockHeader;
 import tech.pegasys.pantheon.ethereum.core.Hash;
 import tech.pegasys.pantheon.ethereum.mainnet.DetachedBlockHeaderValidationRule;
 import tech.pegasys.pantheon.ethereum.mainnet.EthHasher;
-import tech.pegasys.pantheon.ethereum.rlp.RLP;
-import tech.pegasys.pantheon.ethereum.rlp.RlpUtils;
+import tech.pegasys.pantheon.ethereum.rlp.BytesValueRLPOutput;
 import tech.pegasys.pantheon.util.bytes.Bytes32;
 import tech.pegasys.pantheon.util.bytes.BytesValue;
 import tech.pegasys.pantheon.util.bytes.BytesValues;
 import tech.pegasys.pantheon.util.uint.UInt256;
 
 import java.math.BigInteger;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
 public final class ProofOfWorkValidationRule implements DetachedBlockHeaderValidationRule {
 
-  private static final Logger LOG = LogManager.getLogger(ProofOfWorkValidationRule.class);
-
-  private static final int SERIALIZED_HASH_SIZE = 33;
-
-  private static final int SERIALIZED_NONCE_SIZE = 9;
+  private static final Logger LOG = LogManager.getLogger();
 
   private static final BigInteger ETHHASH_TARGET_UPPER_BOUND = BigInteger.valueOf(2).pow(256);
 
   private static final EthHasher HASHER = new EthHasher.Light();
 
-  private static final ThreadLocal<MessageDigest> KECCAK_256 =
-      ThreadLocal.withInitial(
-          () -> {
-            try {
-              return BouncyCastleMessageDigestFactory.create(
-                  tech.pegasys.pantheon.crypto.Hash.KECCAK256_ALG);
-            } catch (final NoSuchAlgorithmException ex) {
-              throw new IllegalStateException(ex);
-            }
-          });
-
   @Override
   public boolean validate(final BlockHeader header, final BlockHeader parent) {
-    final MessageDigest keccak256 = KECCAK_256.get();
-
-    final byte[] bytes = RLP.encode(header::writeTo).extractArray();
-    final int listOffset = RlpUtils.decodeOffset(bytes, 0);
-    final int length = RlpUtils.decodeLength(bytes, 0);
-
-    final byte[] listHeadBuff = new byte[10];
-    final int newLength = length - SERIALIZED_HASH_SIZE - SERIALIZED_NONCE_SIZE;
-    final int sizeLen = writeListPrefix(newLength - listOffset, listHeadBuff);
-
-    keccak256.update(listHeadBuff, 0, sizeLen);
-    keccak256.update(bytes, listOffset, newLength - sizeLen);
     final byte[] hashBuffer = new byte[64];
-    HASHER.hash(hashBuffer, header.getNonce(), header.getNumber(), keccak256.digest());
+    final Hash headerHash = hashHeader(header);
+    HASHER.hash(hashBuffer, header.getNonce(), header.getNumber(), headerHash.extractArray());
 
     if (header.getDifficulty().isZero()) {
       LOG.trace("Rejecting header because difficulty is 0");
@@ -105,19 +75,31 @@ public final class ProofOfWorkValidationRule implements DetachedBlockHeaderValid
     return true;
   }
 
+  private Hash hashHeader(final BlockHeader header) {
+    final BytesValueRLPOutput out = new BytesValueRLPOutput();
+
+    // Encode header without nonce and mixhash
+    out.startList();
+    out.writeBytesValue(header.getParentHash());
+    out.writeBytesValue(header.getOmmersHash());
+    out.writeBytesValue(header.getCoinbase());
+    out.writeBytesValue(header.getStateRoot());
+    out.writeBytesValue(header.getTransactionsRoot());
+    out.writeBytesValue(header.getReceiptsRoot());
+    out.writeBytesValue(header.getLogsBloom().getBytes());
+    out.writeUInt256Scalar(header.getDifficulty());
+    out.writeLongScalar(header.getNumber());
+    out.writeLongScalar(header.getGasLimit());
+    out.writeLongScalar(header.getGasUsed());
+    out.writeLongScalar(header.getTimestamp());
+    out.writeBytesValue(header.getExtraData());
+    out.endList();
+
+    return Hash.hash(out.encoded());
+  }
+
   @Override
   public boolean includeInLightValidation() {
     return false;
   }
-
-  private static int writeListPrefix(final int size, final byte[] target) {
-    final int sizeLength = 4 - Integer.numberOfLeadingZeros(size) / 8;
-    target[0] = (byte) (0xf7 + sizeLength);
-    int shift = 0;
-    for (int i = 0; i < sizeLength; i++) {
-      target[sizeLength - i] = (byte) (size >> shift);
-      shift += 8;
-    }
-    return 1 + sizeLength;
-  }
 }

ethereum/core/src/test/java/tech/pegasys/pantheon/ethereum/mainnet/headervalidationrules/ProofOfWorkValidationRuleTest.java

@@ -0,0 +1,115 @@
+/*
+ * Copyright 2018 ConsenSys AG.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+package tech.pegasys.pantheon.ethereum.mainnet.headervalidationrules;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import tech.pegasys.pantheon.ethereum.core.BlockHashFunction;
+import tech.pegasys.pantheon.ethereum.core.BlockHeader;
+import tech.pegasys.pantheon.ethereum.core.BlockHeaderBuilder;
+import tech.pegasys.pantheon.ethereum.core.Hash;
+import tech.pegasys.pantheon.ethereum.mainnet.MainnetProtocolSchedule;
+import tech.pegasys.pantheon.ethereum.mainnet.ProtocolSchedule;
+import tech.pegasys.pantheon.ethereum.mainnet.ScheduleBasedBlockHashFunction;
+import tech.pegasys.pantheon.ethereum.mainnet.ValidationTestUtils;
+import tech.pegasys.pantheon.util.uint.UInt256;
+
+import java.io.IOException;
+import java.math.BigInteger;
+import java.util.Arrays;
+import java.util.Collection;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+
+@RunWith(Parameterized.class)
+public class ProofOfWorkValidationRuleTest {
+
+  private final BlockHeader blockHeader;
+  private final BlockHeader parentHeader;
+  private final ProofOfWorkValidationRule validationRule;
+
+  public ProofOfWorkValidationRuleTest(final long parentBlockNum, final long blockNum)
+      throws IOException {
+    blockHeader = ValidationTestUtils.readHeader(parentBlockNum);
+    parentHeader = ValidationTestUtils.readHeader(blockNum);
+    validationRule = new ProofOfWorkValidationRule();
+  }
+
+  @Parameters(name = "block {1}")
+  public static Collection<Object[]> data() {
+
+    return Arrays.asList(
+        new Object[][] {
+          {300005, 300006},
+          {1200000, 1200001},
+          {4400000, 4400001},
+          {4400001, 4400002}
+        });
+  }
+
+  @Test
+  public void validatesValidBlocks() {
+    assertThat(validationRule.validate(blockHeader, parentHeader)).isTrue();
+  }
+
+  @Test
+  public void failsBlockWithZeroValuedDifficulty() {
+    BlockHeader header =
+        BlockHeaderBuilder.fromHeader(blockHeader)
+            .difficulty(UInt256.ZERO)
+            .blockHashFunction(mainnetBlockHashFunction())
+            .buildBlockHeader();
+    assertThat(validationRule.validate(header, parentHeader)).isFalse();
+  }
+
+  @Test
+  public void failsWithVeryLargeDifficulty() {
+    UInt256 largeDifficulty = UInt256.of(BigInteger.valueOf(2).pow(255));
+    BlockHeader header =
+        BlockHeaderBuilder.fromHeader(blockHeader)
+            .difficulty(largeDifficulty)
+            .blockHashFunction(mainnetBlockHashFunction())
+            .buildBlockHeader();
+    assertThat(validationRule.validate(header, parentHeader)).isFalse();
+  }
+
+  @Test
+  public void failsWithMisMatchedMixHash() {
+    Hash updateMixHash = Hash.wrap(blockHeader.getMixHash().asUInt256().minus(1L).getBytes());
+    BlockHeader header =
+        BlockHeaderBuilder.fromHeader(blockHeader)
+            .mixHash(updateMixHash)
+            .blockHashFunction(mainnetBlockHashFunction())
+            .buildBlockHeader();
+    assertThat(validationRule.validate(header, parentHeader)).isFalse();
+  }
+
+  @Test
+  public void failsWithMisMatchedNonce() {
+    long updatedNonce = blockHeader.getNonce() + 1;
+    BlockHeader header =
+        BlockHeaderBuilder.fromHeader(blockHeader)
+            .nonce(updatedNonce)
+            .blockHashFunction(mainnetBlockHashFunction())
+            .buildBlockHeader();
+    assertThat(validationRule.validate(header, parentHeader)).isFalse();
+  }
+
+  private BlockHashFunction mainnetBlockHashFunction() {
+    ProtocolSchedule<Void> protocolSchedule = MainnetProtocolSchedule.create();
+    return ScheduleBasedBlockHashFunction.create(protocolSchedule);
+  }
+}