alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (IpSubnetFilterRule.java)

This example Java source code file (IpSubnetFilterRule.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

biginteger, illegalargumentexception, ip4subnetfilterrule, ip6subnetfilterrule, ipfilterrule, ipfilterruletype, ipsubnetfilterrule, ipv4, ipv6, math, net, network, nullpointerexception, only, override, the, unknownhostexception

The IpSubnetFilterRule.java Java example source code

/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project 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 io.netty.handler.ipfilter;

import java.math.BigInteger;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.UnknownHostException;

/**
 * Use this class to create rules for {@link RuleBasedIpFilter} that group IP addresses into subnets.
 * Supports both, IPv4 and IPv6.
 */
public final class IpSubnetFilterRule implements IpFilterRule {

    private final IpFilterRule filterRule;

    public IpSubnetFilterRule(String ipAddress, int cidrPrefix, IpFilterRuleType ruleType) {
        try {
            filterRule = selectFilterRule(InetAddress.getByName(ipAddress), cidrPrefix, ruleType);
        } catch (UnknownHostException e) {
            throw new IllegalArgumentException("ipAddress", e);
        }
    }

    public IpSubnetFilterRule(InetAddress ipAddress, int cidrPrefix, IpFilterRuleType ruleType) {
        filterRule = selectFilterRule(ipAddress, cidrPrefix, ruleType);
    }

    private static IpFilterRule selectFilterRule(InetAddress ipAddress, int cidrPrefix, IpFilterRuleType ruleType) {
        if (ipAddress == null) {
            throw new NullPointerException("ipAddress");
        }

        if (ruleType == null) {
            throw new NullPointerException("ruleType");
        }

        if (ipAddress instanceof Inet4Address) {
            return new Ip4SubnetFilterRule((Inet4Address) ipAddress, cidrPrefix, ruleType);
        } else if (ipAddress instanceof Inet6Address) {
            return new Ip6SubnetFilterRule((Inet6Address) ipAddress, cidrPrefix, ruleType);
        } else {
            throw new IllegalArgumentException("Only IPv4 and IPv6 addresses are supported");
        }
    }

    @Override
    public boolean matches(InetSocketAddress remoteAddress) {
        return filterRule.matches(remoteAddress);
    }

    @Override
    public IpFilterRuleType ruleType() {
        return filterRule.ruleType();
    }

    private static final class Ip4SubnetFilterRule implements IpFilterRule {

        private final int networkAddress;
        private final int subnetMask;
        private final IpFilterRuleType ruleType;

        private Ip4SubnetFilterRule(Inet4Address ipAddress, int cidrPrefix, IpFilterRuleType ruleType) {
            if (cidrPrefix < 0 || cidrPrefix > 32) {
                throw new IllegalArgumentException(String.format("IPv4 requires the subnet prefix to be in range of " +
                                                                    "[0,32]. The prefix was: %d", cidrPrefix));
            }

            subnetMask = prefixToSubnetMask(cidrPrefix);
            networkAddress = ipToInt(ipAddress) & subnetMask;
            this.ruleType = ruleType;
        }

        @Override
        public boolean matches(InetSocketAddress remoteAddress) {
            int ipAddress = ipToInt((Inet4Address) remoteAddress.getAddress());

            return (ipAddress & subnetMask) == networkAddress;
        }

        @Override
        public IpFilterRuleType ruleType() {
            return ruleType;
        }

        private static int ipToInt(Inet4Address ipAddress) {
            byte[] octets = ipAddress.getAddress();
            assert octets.length == 4;

            return (octets[0] & 0xff) << 24 |
                   (octets[1] & 0xff) << 16 |
                   (octets[2] & 0xff) << 8 |
                    octets[3] & 0xff;
        }

        private static int prefixToSubnetMask(int cidrPrefix) {
            /**
             * Perform the shift on a long and downcast it to int afterwards.
             * This is necessary to handle a cidrPrefix of zero correctly.
             * The left shift operator on an int only uses the five least
             * significant bits of the right-hand operand. Thus -1 << 32 evaluates
             * to -1 instead of 0. The left shift operator applied on a long
             * uses the six least significant bits.
             *
             * Also see https://github.com/netty/netty/issues/2767
             */
            return (int) ((-1L << 32 - cidrPrefix) & 0xffffffff);
        }
    }

    private static final class Ip6SubnetFilterRule implements IpFilterRule {

        private static final BigInteger MINUS_ONE = BigInteger.valueOf(-1);

        private final BigInteger networkAddress;
        private final BigInteger subnetMask;
        private final IpFilterRuleType ruleType;

        private Ip6SubnetFilterRule(Inet6Address ipAddress, int cidrPrefix, IpFilterRuleType ruleType) {
            if (cidrPrefix < 0 || cidrPrefix > 128) {
                throw new IllegalArgumentException(String.format("IPv6 requires the subnet prefix to be in range of " +
                                                                    "[0,128]. The prefix was: %d", cidrPrefix));
            }

            subnetMask = prefixToSubnetMask(cidrPrefix);
            networkAddress = ipToInt(ipAddress).and(subnetMask);
            this.ruleType = ruleType;
        }

        @Override
        public boolean matches(InetSocketAddress remoteAddress) {
            BigInteger ipAddress = ipToInt((Inet6Address) remoteAddress.getAddress());

            return ipAddress.and(subnetMask).equals(networkAddress);
        }

        @Override
        public IpFilterRuleType ruleType() {
            return ruleType;
        }

        private static BigInteger ipToInt(Inet6Address ipAddress) {
            byte[] octets = ipAddress.getAddress();
            assert octets.length == 16;

            return new BigInteger(octets);
        }

        private static BigInteger prefixToSubnetMask(int cidrPrefix) {
            return MINUS_ONE.shiftLeft(128 - cidrPrefix);
        }
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java IpSubnetFilterRule.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.