org.apache.commons.id.uuid.state.StateHelper Maven / Gradle / Ivy
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* 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.commons.id.uuid.state;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Collection;
import java.util.Iterator;
import java.util.Random;
import java.util.StringTokenizer;
import org.apache.commons.id.DecoderException;
import org.apache.commons.discovery.tools.DiscoverClass;
import org.apache.commons.id.uuid.Bytes;
import org.apache.commons.id.uuid.Constants;
import org.apache.commons.id.uuid.clock.Clock;
import org.apache.commons.id.uuid.clock.OverClockedException;
import org.apache.commons.id.DigestUtils;
import org.apache.commons.id.Hex;
/**
* StateHelper provides helper methods for the uuid state
* implementations.
*
* @author Commons-Id team
* @version $Id: StateHelper.java 480488 2006-11-29 08:57:26Z bayard $
*/
public final class StateHelper implements Constants {
/** The key for the System.property containing the ClockImpl String. */
public static final String UUID_CLOCK_IMPL_PROPERTY_KEY = Clock.class.getName();
/** The key for the System.property containing the StateImpl String. */
public static final String UUID_STATE_IMPL_PROPERTY_KEY = State.class.getName();
/** Array length of node bytes. */
public static final int NODE_ID_BYTE_LENGTH = 6;
/** Number of bytes in a short. */
public static final short BYTES_IN_SHORT = 2;
/** Number of postitions to shift when shifting by one byte. */
public static final short SHIFT_BY_BYTE = 8;
/** Number of postitions to shift when shifting by one byte. */
public static final short HOSTNAME_MAX_CHAR_LEN = 255;
/** OR-Mask to set the node's multicast bit true. */
private static final int MULTICAST_BIT_SET = 0x80;
/** The maximum character length of a long */
private static final short LONG_CHAR_LEN = 19;
/** Standard one page buffer size */
private static final int BUF_PAGE_SZ = 1024;
/** Start of the XML document used to store state persistence in XML */
protected static final String XML_DOC_START = ""
+ "\n\n"
+ " \n"
+ " \n"
+ " \n"
+ " \n]>"
+ "\n";
/** Start of XML node tag */
protected static final String XML_NODE_TAG_START = "\n\t ";
/** Number of tokens in a MAC address with "-" as separator */
private static final short MAC_ADDRESS_TOKEN_COUNT = 6;
/** String length of a MAC address with "-" as separator */
private static final short MAC_ADDRESS_CHAR_LENGTH = 17;
/** Default constructor */
private StateHelper() {
super();
}
/**
* Creates a Random node identifier as described in IEFT UUID URN
* specification.
*
* @return a random node idenfifier based on MD5 of system information.
*/
public static byte[] randomNodeIdentifier() {
//Holds the 16 byte MD5 value
byte[] seed = new byte[UUID_BYTE_LENGTH];
//Set the initial string buffer capacity
//Time + Object.hashCode + HostName + Guess of all system properties
int bufSize = (LONG_CHAR_LEN * 2) + HOSTNAME_MAX_CHAR_LEN + (2 * BUF_PAGE_SZ);
StringBuffer randInfo = new StringBuffer(bufSize);
//Add current time
long time = 0;
try {
time = getClockImpl().getUUIDTime();
} catch (OverClockedException oce) {
time = System.currentTimeMillis();
}
randInfo.append(time);
//Add hostname
try {
InetAddress address = InetAddress.getLocalHost();
randInfo.append(address.getHostName());
} catch (UnknownHostException ukhe) {
randInfo.append("Host Unknown");
}
//Add something else "random"
randInfo.append(new Object().hashCode());
//Add system properties
Collection info = System.getProperties().values();
Iterator it = info.iterator();
while (it.hasNext()) {
randInfo.append(it.next());
}
//MD5 Hash code the system information to get a node id.
seed = DigestUtils.md5(randInfo.toString());
//Return upper 6 bytes of hash
byte[] raw = new byte[NODE_ID_BYTE_LENGTH];
System.arraycopy(seed, 0, raw, 0, NODE_ID_BYTE_LENGTH);
//Per draft set multi-cast bit true
raw[0] |= MULTICAST_BIT_SET;
return raw;
}
/**
* Generates a new security quality random clock sequence.
*
* @return a new security quality random clock sequence.
*/
public static short newClockSequence() {
Random random = new Random();
byte[] bytes = new byte[BYTES_IN_SHORT];
random.nextBytes(bytes);
return (short) (Bytes.toShort(bytes) & 0x3FFF);
}
/**
* Returns the Clock implementation using commons discovery.
*
* @return the Clock implementation using commons discovery.
*/
public static Clock getClockImpl() {
Clock c = null;
try {
DiscoverClass dc = new DiscoverClass();
c = (Clock) dc.newInstance(
Clock.class,
Clock.DEFAULT_CLOCK_IMPL);
} catch (Exception ex) {
// ignore as default implementation will be used.
}
return c;
}
/**
* Returns the State implementation in use.
*
* @return the State implementation in use.
*/
public static State getStateImpl() {
State s = null;
try {
DiscoverClass dc = new DiscoverClass();
s = (State) dc.newInstance(
State.class,
State.DEFAULT_STATE_IMPL);
} catch (Exception ex) {
// ignore as default implementation will be used.
}
return s;
}
/**
* Utility method decodes a valid MAC address in the form of
* XX-XX-XX-XX-XX-XX where each XX represents a hexidecimal value.
*
* Returns null if the address can not be decoded.
*
* @param address the String hexidecimal dash separated MAC address.
* @return a byte array representing the the address. Null if not a valid address.
*/
public static byte[] decodeMACAddress(String address) {
StringBuffer buf = new StringBuffer(MAC_ADDRESS_TOKEN_COUNT * 2);
StringTokenizer tokens = new StringTokenizer(address, "-");
if (tokens.countTokens() != MAC_ADDRESS_TOKEN_COUNT) {
return null;
} else {
for (int i = 0; i < MAC_ADDRESS_TOKEN_COUNT; i++) {
buf.append(tokens.nextToken());
}
}
try {
char[] c = buf.toString().toCharArray();
return Hex.decodeHex(c);
} catch (DecoderException de) {
de.printStackTrace();
return null;
}
}
/**
* Returns the node id / address byte array in it's hexidecimal string
* representation in the following format: XX-XX-XX-XX-XX-XX where each XX
* represents a hexidecimal value.
*
* @param address the 6 byte node id / address.
* @return the node id /address byte array in as hexidecimal with dash
* separating each octet.
* @throws IOException an Input Output Exception.
*/
public static String encodeMACAddress(byte[] address) throws IOException {
char[] chars = Hex.encodeHex(address);
StringBuffer buf = new StringBuffer(MAC_ADDRESS_CHAR_LENGTH);
for (int i = 0; i < chars.length; i++) {
buf.append(chars[i]);
if (i != chars.length - 1 && i % 2 != 0) {
buf.append("-");
}
}
return buf.toString().toUpperCase();
}
}
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