org.apache.jackrabbit.core.data.AbstractDataStore Maven / Gradle / Ivy
/*
* 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.jackrabbit.core.data;
import java.security.SecureRandom;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public abstract class AbstractDataStore implements DataStore {
private static Logger LOG = LoggerFactory.getLogger(AbstractDataStore.class);
private static final String ALGORITHM = "HmacSHA1";
/**
* Array of hexadecimal digits.
*/
private static final char[] HEX = "0123456789abcdef".toCharArray();
/**
* The digest algorithm used to uniquely identify records.
*/
protected String DIGEST = System.getProperty("ds.digest.algorithm", "SHA-256");
/**
* Cached copy of the reference key of this data store. Initialized in
* {@link #getReferenceKey()} when the key is first accessed.
*/
private byte[] referenceKey = null;
//---------------------------------------------------------< DataStore >--
public DataRecord getRecord(DataIdentifier identifier)
throws DataStoreException {
DataRecord record = getRecordIfStored(identifier);
if (record != null) {
return record;
} else {
throw new DataStoreException(
"Record " + identifier + " does not exist");
}
}
public DataRecord getRecordFromReference(String reference)
throws DataStoreException {
if (reference != null) {
int colon = reference.indexOf(':');
if (colon != -1) {
DataIdentifier identifier =
new DataIdentifier(reference.substring(0, colon));
if (reference.equals(getReferenceFromIdentifier(identifier))) {
return getRecordIfStored(identifier);
}
}
}
return null;
}
//---------------------------------------------------------< protected >--
/**
* Returns the hex encoding of the given bytes.
*
* @param value value to be encoded
* @return encoded value
*/
protected static String encodeHexString(byte[] value) {
char[] buffer = new char[value.length * 2];
for (int i = 0; i < value.length; i++) {
buffer[2 * i] = HEX[(value[i] >> 4) & 0x0f];
buffer[2 * i + 1] = HEX[value[i] & 0x0f];
}
return new String(buffer);
}
protected String getReferenceFromIdentifier(DataIdentifier identifier) {
try {
String id = identifier.toString();
Mac mac = Mac.getInstance(ALGORITHM);
mac.init(new SecretKeySpec(getReferenceKey(), ALGORITHM));
byte[] hash = mac.doFinal(id.getBytes("UTF-8"));
return id + ':' + encodeHexString(hash);
} catch (Exception e) {
LOG.error("Failed to hash identifier using MAC (Message Authentication Code) algorithm.", e);
}
return null;
}
/**
* Returns the reference key of this data store. If one does not already
* exist, it is automatically created in an implementation-specific way.
* The default implementation simply creates a temporary random key that's
* valid only until the data store gets restarted. Subclasses can override
* and/or decorate this method to support a more persistent reference key.
*
* This method is called only once during the lifetime of a data store
* instance and the return value is cached in memory, so it's no problem
* if the implementation is slow.
*
* @return reference key
* @throws DataStoreException if the key is not available
*/
protected byte[] getOrCreateReferenceKey() throws DataStoreException {
byte[] referenceKeyValue = new byte[256];
new SecureRandom().nextBytes(referenceKeyValue);
return referenceKeyValue;
}
//-----------------------------------------------------------< private >--
/**
* Returns the reference key of this data store. Synchronized to
* control concurrent access to the cached {@link #referenceKey} value.
*
* @return reference key
* @throws DataStoreException if the key is not available
*/
private synchronized byte[] getReferenceKey() throws DataStoreException {
if (referenceKey == null) {
referenceKey = getOrCreateReferenceKey();
}
return referenceKey;
}
}