/*
* 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.catalina.tribes.util;
import java.security.SecureRandom;
import java.util.Random;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
/**
* Smple generation of a UUID.
*/
public class UUIDGenerator {
private static final Log log = LogFactory.getLog(UUIDGenerator.class);
protected static final StringManager sm = StringManager.getManager("org.apache.catalina.tribes.util");
public static final int UUID_LENGTH = 16;
public static final int UUID_VERSION = 4;
public static final int BYTES_PER_INT = 4;
public static final int BITS_PER_BYTE = 8;
protected static final SecureRandom secrand;
protected static final Random rand = new Random();
static {
long start = System.currentTimeMillis();
secrand = new SecureRandom();
// seed the generator
secrand.nextInt();
long time = System.currentTimeMillis() - start;
if (time > 100) {
log.info(sm.getString("uuidGenerator.createRandom", secrand.getAlgorithm(), Long.valueOf(time)));
}
}
public static byte[] randomUUID(boolean secure) {
byte[] result = new byte[UUID_LENGTH];
return randomUUID(secure, result, 0);
}
public static byte[] randomUUID(boolean secure, byte[] into, int offset) {
if ((offset + UUID_LENGTH) > into.length) {
throw new ArrayIndexOutOfBoundsException(
sm.getString("uuidGenerator.unable.fit", Integer.toString(UUID_LENGTH),
Integer.toString(into.length), Integer.toString(offset + UUID_LENGTH)));
}
Random r = (secure && (secrand != null)) ? secrand : rand;
nextBytes(into, offset, UUID_LENGTH, r);
into[6 + offset] &= 0x0F;
into[6 + offset] |= (UUID_VERSION << 4);
into[8 + offset] &= 0x3F; // 0011 1111
into[8 + offset] |= (byte) 0x80; // 1000 0000
return into;
}
/**
* Same as java.util.Random.nextBytes except this one we don't have to allocate a new byte array
*
* @param into byte[]
* @param offset int
* @param length int
* @param r Random
*/
public static void nextBytes(byte[] into, int offset, int length, Random r) {
int numGot = 0, rnd = 0;
while (true) {
for (int i = 0; i < BYTES_PER_INT; i++) {
if (numGot == length) {
return;
}
rnd = (i == 0 ? r.nextInt() : rnd >> BITS_PER_BYTE);
into[offset + numGot] = (byte) rnd;
numGot++;
}
}
}
}