93 lines
3.3 KiB
Java
93 lines
3.3 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.catalina.tribes.util;
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import java.security.SecureRandom;
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import java.util.Random;
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import org.apache.juli.logging.Log;
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import org.apache.juli.logging.LogFactory;
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/**
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* simple generation of a UUID
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* @version 1.0
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*/
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public class UUIDGenerator {
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private static final Log log = LogFactory.getLog(UUIDGenerator.class);
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protected static final StringManager sm =
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StringManager.getManager("org.apache.catalina.tribes.util");
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public static final int UUID_LENGTH = 16;
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public static final int UUID_VERSION = 4;
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public static final int BYTES_PER_INT = 4;
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public static final int BITS_PER_BYTE = 8;
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protected static final SecureRandom secrand;
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protected static final Random rand = new Random();
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static {
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long start = System.currentTimeMillis();
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secrand = new SecureRandom();
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// seed the generator
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secrand.nextInt();
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long time = System.currentTimeMillis() - start;
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if (time > 100) {
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log.info(sm.getString("uuidGenerator.createRandom",
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secrand.getAlgorithm(), Long.valueOf(time)));
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}
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}
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public static byte[] randomUUID(boolean secure) {
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byte[] result = new byte[UUID_LENGTH];
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return randomUUID(secure,result,0);
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}
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public static byte[] randomUUID(boolean secure, byte[] into, int offset) {
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if ( (offset+UUID_LENGTH)>into.length )
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throw new ArrayIndexOutOfBoundsException(sm.getString("uuidGenerator.unable.fit",
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Integer.toString(UUID_LENGTH), Integer.toString(into.length),
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Integer.toString(offset+UUID_LENGTH)));
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Random r = (secure&&(secrand!=null))?secrand:rand;
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nextBytes(into,offset,UUID_LENGTH,r);
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into[6+offset] &= 0x0F;
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into[6+offset] |= (UUID_VERSION << 4);
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into[8+offset] &= 0x3F; //0011 1111
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into[8+offset] |= 0x80; //1000 0000
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return into;
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}
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/**
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* Same as java.util.Random.nextBytes except this one we dont have to allocate a new byte array
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* @param into byte[]
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* @param offset int
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* @param length int
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* @param r Random
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*/
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public static void nextBytes(byte[] into, int offset, int length, Random r) {
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int numRequested = length;
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int numGot = 0, rnd = 0;
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while (true) {
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for (int i = 0; i < BYTES_PER_INT; i++) {
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if (numGot == numRequested) return;
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rnd = (i == 0 ? r.nextInt() : rnd >> BITS_PER_BYTE);
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into[offset+numGot] = (byte) rnd;
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numGot++;
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}
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}
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}
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} |