net.ripe.commons.ip.ConservativePrefixFinder Maven / Gradle / Ivy
/**
* The MIT License (MIT)
*
* Copyright (c) 2011-2014, Yannis Gonianakis
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package net.ripe.commons.ip;
import java.math.BigInteger;
import java.util.Collection;
public class ConservativePrefixFinder extends PrefixFinder {
public static ConservativePrefixFinder newInstance() {
return new ConservativePrefixFinder();
}
private ConservativePrefixFinder() {
super(new ConservativeStrategy());
}
private static class ConservativeStrategy implements Strategy {
@Override
public Ipv6Range findPrefixOrNull(int prefixLength, Collection ranges) {
final BigInteger desiredPrefixSize = BigInteger.valueOf(2).pow(128 - prefixLength);
Ipv6Range foundPrefix = null;
BigInteger currentSize = null;
for (Ipv6Range freeBlock : ranges) {
if (freeBlock.size().compareTo(desiredPrefixSize) >= 0) {
final Optional smallestPrefix = PrefixUtils.findMinimumPrefixForPrefixLength(freeBlock, prefixLength);
if (smallestPrefix.isPresent()) {
final Ipv6Range candidatePrefix = smallestPrefix.get();
final BigInteger candidateSize = candidatePrefix.size();
if ((foundPrefix == null) || candidateSize.compareTo(currentSize) < 0) {
foundPrefix = candidatePrefix;
currentSize = candidateSize;
}
}
}
}
return foundPrefix == null ? null : Ipv6Range.from(foundPrefix.start()).andPrefixLength(prefixLength);
}
}
}