content: /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you 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 org.apache.bookkeeper.proto.checksum;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufAllocator;
  import java.security.GeneralSecurityException;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Arrays;
  import javax.crypto.Mac;
  import javax.crypto.spec.SecretKeySpec;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A {@code SHA-1} based digest manager.
   *
   * <p>NOTE: This class is tended to be used by this project only. External users should not rely on it directly.
   */
  public class MacDigestManager extends DigestManager {
      private static final Logger LOG = LoggerFactory.getLogger(MacDigestManager.class);
  
      public static final String DIGEST_ALGORITHM = "SHA-1";
      public static final String KEY_ALGORITHM = "HmacSHA1";
  
      public static final int MAC_CODE_LENGTH = 20;
  
      final byte[] passwd;
  
      static final byte[] EMPTY_LEDGER_KEY;
      static {
          try {
              EMPTY_LEDGER_KEY = MacDigestManager.genDigest("ledger", new byte[0]);
          } catch (NoSuchAlgorithmException e) {
              throw new RuntimeException(e);
          }
      }
  
      private final ThreadLocal<Mac> mac = new ThreadLocal<Mac>() {
          @Override
          protected Mac initialValue() {
              try {
                  byte[] macKey = genDigest("mac", passwd);
                  SecretKeySpec keySpec = new SecretKeySpec(macKey, KEY_ALGORITHM);
                  Mac mac = Mac.getInstance(KEY_ALGORITHM);
                  mac.init(keySpec);
                  return mac;
              } catch (GeneralSecurityException gse) {
                  LOG.error("Couldn't not get mac instance", gse);
                  return null;
              }
          }
      };
  
      public MacDigestManager(long ledgerId, byte[] passwd, boolean useV2Protocol, ByteBufAllocator allocator)
              throws GeneralSecurityException {
          super(ledgerId, useV2Protocol, allocator);
          this.passwd = Arrays.copyOf(passwd, passwd.length);
      }
  
      public static byte[] genDigest(String pad, byte[] passwd) throws NoSuchAlgorithmException {
          MessageDigest digest = MessageDigest.getInstance(DIGEST_ALGORITHM);
          digest.update(pad.getBytes(UTF_8));
          digest.update(passwd);
          return digest.digest();
      }
  
      @Override
      int getMacCodeLength() {
          return MAC_CODE_LENGTH;
      }
  
  
      @Override
      void populateValueAndReset(int digest, ByteBuf buffer) {
          buffer.writeBytes(mac.get().doFinal());
      }
  
      @Override
      int internalUpdate(int digest, ByteBuf data, int offset, int len) {
          mac.get().update(data.slice(offset, len).nioBuffer());
          return 0;
      }
  
      @Override
      int internalUpdate(int digest, byte[] buffer, int offset, int len) {
          mac.get().update(buffer, offset, len);
          return 0;
      }
  
      @Override
      boolean isInt32Digest() {
          return false;
      }
  
      @Override
      boolean acceptsMemoryAddressBuffer() {
          return false;
      }
  }
  