    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.net.util;
    018
    019import java.util.regex.Matcher;
    020import java.util.regex.Pattern;
    021
    022/**
    023 * A class that performs some subnet calculations given a network address and a subnet mask.
    024 * @see "http://www.faqs.org/rfcs/rfc1519.html"
    025 * @author <rwinston@apache.org>
    026 * @since 2.0
    027 */
    028public class SubnetUtils {
    029
    030    private static final String IP_ADDRESS = "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})";
    031    private static final String SLASH_FORMAT = IP_ADDRESS + "/(\\d{1,3})";
    032    private static final Pattern addressPattern = Pattern.compile(IP_ADDRESS);
    033    private static final Pattern cidrPattern = Pattern.compile(SLASH_FORMAT);
    034    private static final int NBITS = 32;
    035
    036    private int netmask = 0;
    037    private int address = 0;
    038    private int network = 0;
    039    private int broadcast = 0;
    040
    041    /** Whether the broadcast/network address are included in host count */
    042    private boolean inclusiveHostCount = false;
    043
    044
    045    /**
    046     * Constructor that takes a CIDR-notation string, e.g. "192.168.0.1/16"
    047     * @param cidrNotation A CIDR-notation string, e.g. "192.168.0.1/16"
    048     * @throws IllegalArgumentException if the parameter is invalid,
    049     * i.e. does not match n.n.n.n/m where n=1-3 decimal digits, m = 1-3 decimal digits in range 1-32
    050     */
    051    public SubnetUtils(String cidrNotation) {
    052        calculate(cidrNotation);
    053    }
    054
    055    /**
    056     * Constructor that takes a dotted decimal address and a dotted decimal mask.
    057     * @param address An IP address, e.g. "192.168.0.1"
    058     * @param mask A dotted decimal netmask e.g. "255.255.0.0"
    059     * @throws IllegalArgumentException if the address or mask is invalid,
    060     * i.e. does not match n.n.n.n where n=1-3 decimal digits and the mask is not all zeros
    061     */
    062    public SubnetUtils(String address, String mask) {
    063        calculate(toCidrNotation(address, mask));
    064    }
    065
    066
    067    /**
    068     * Returns <code>true</code> if the return value of {@link SubnetInfo#getAddressCount()}
    069     * includes the network address and broadcast addresses.
    070     * @since 2.2
    071     */
    072    public boolean isInclusiveHostCount() {
    073        return inclusiveHostCount;
    074    }
    075
    076    /**
    077     * Set to <code>true</code> if you want the return value of {@link SubnetInfo#getAddressCount()}
    078     * to include the network and broadcast addresses.
    079     * @param inclusiveHostCount
    080     * @since 2.2
    081     */
    082    public void setInclusiveHostCount(boolean inclusiveHostCount) {
    083        this.inclusiveHostCount = inclusiveHostCount;
    084    }
    085
    086
    087
    088    /**
    089     * Convenience container for subnet summary information.
    090     *
    091     */
    092    public final class SubnetInfo {
    093        private SubnetInfo() {}
    094
    095        private int netmask()       { return netmask; }
    096        private int network()       { return network; }
    097        private int address()       { return address; }
    098        private int broadcast()     { return broadcast; }
    099
    100        private int low() {
    101            return (isInclusiveHostCount() ? network() :
    102                broadcast() - network() > 1 ? network() + 1 : 0);
    103        }
    104
    105        private int high() {
    106            return (isInclusiveHostCount() ? broadcast() :
    107                broadcast() - network() > 1 ? broadcast() -1  : 0);
    108        }
    109
    110        /**
    111         * Returns true if the parameter <code>address</code> is in the
    112         * range of usable endpoint addresses for this subnet. This excludes the
    113         * network and broadcast adresses.
    114         * @param address A dot-delimited IPv4 address, e.g. "192.168.0.1"
    115         * @return True if in range, false otherwise
    116         */
    117        public boolean isInRange(String address) {
    118            return isInRange(toInteger(address));
    119        }
    120
    121        private boolean isInRange(int address) {
    122            int diff = address - low();
    123            return (diff >= 0 && (diff <= (high() - low())));
    124        }
    125
    126        public String getBroadcastAddress() {
    127            return format(toArray(broadcast()));
    128        }
    129
    130        public String getNetworkAddress() {
    131            return format(toArray(network()));
    132        }
    133
    134        public String getNetmask() {
    135            return format(toArray(netmask()));
    136        }
    137
    138        public String getAddress() {
    139            return format(toArray(address()));
    140        }
    141
    142        /**
    143         * Return the low address as a dotted IP address.
    144         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
    145         *
    146         * @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
    147         */
    148        public String getLowAddress() {
    149            return format(toArray(low()));
    150        }
    151
    152        /**
    153         * Return the high address as a dotted IP address.
    154         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
    155         *
    156         * @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
    157         */
    158        public String getHighAddress() {
    159            return format(toArray(high()));
    160        }
    161
    162        /**
    163         * Get the count of available addresses.
    164         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
    165         * @return the count of addresses, may be zero.
    166         */
    167        public int getAddressCount()                {
    168            int count = broadcast() - network() + (isInclusiveHostCount() ? 1 : -1);
    169            return count < 0 ? 0 : count;
    170        }
    171
    172        public int asInteger(String address) {
    173            return toInteger(address);
    174        }
    175
    176        public String getCidrSignature() {
    177            return toCidrNotation(
    178                    format(toArray(address())),
    179                    format(toArray(netmask()))
    180            );
    181        }
    182
    183        public String[] getAllAddresses() {
    184            int ct = getAddressCount();
    185            String[] addresses = new String[ct];
    186            if (ct == 0) {
    187                return addresses;
    188            }
    189            for (int add = low(), j=0; add <= high(); ++add, ++j) {
    190                addresses[j] = format(toArray(add));
    191            }
    192            return addresses;
    193        }
    194
    195        /**
    196         * {@inheritDoc}
    197         * @since 2.2
    198         */
    199        @Override
    200        public String toString() {
    201            final StringBuilder buf = new StringBuilder();
    202            buf.append("CIDR Signature:\t[").append(getCidrSignature()).append("]")
    203                .append(" Netmask: [").append(getNetmask()).append("]\n")
    204                .append("Network:\t[").append(getNetworkAddress()).append("]\n")
    205                .append("Broadcast:\t[").append(getBroadcastAddress()).append("]\n")
    206                 .append("First Address:\t[").append(getLowAddress()).append("]\n")
    207                 .append("Last Address:\t[").append(getHighAddress()).append("]\n")
    208                 .append("# Addresses:\t[").append(getAddressCount()).append("]\n");
    209            return buf.toString();
    210        }
    211    }
    212
    213    /**
    214     * Return a {@link SubnetInfo} instance that contains subnet-specific statistics
    215     * @return new instance
    216     */
    217    public final SubnetInfo getInfo() { return new SubnetInfo(); }
    218
    219    /*
    220     * Initialize the internal fields from the supplied CIDR mask
    221     */
    222    private void calculate(String mask) {
    223        Matcher matcher = cidrPattern.matcher(mask);
    224
    225        if (matcher.matches()) {
    226            address = matchAddress(matcher);
    227
    228            /* Create a binary netmask from the number of bits specification /x */
    229            int cidrPart = rangeCheck(Integer.parseInt(matcher.group(5)), 0, NBITS);
    230            for (int j = 0; j < cidrPart; ++j) {
    231                netmask |= (1 << 31-j);
    232            }
    233
    234            /* Calculate base network address */
    235            network = (address & netmask);
    236
    237            /* Calculate broadcast address */
    238            broadcast = network | ~(netmask);
    239        } else {
    240            throw new IllegalArgumentException("Could not parse [" + mask + "]");
    241        }
    242    }
    243
    244    /*
    245     * Convert a dotted decimal format address to a packed integer format
    246     */
    247    private int toInteger(String address) {
    248        Matcher matcher = addressPattern.matcher(address);
    249        if (matcher.matches()) {
    250            return matchAddress(matcher);
    251        } else {
    252            throw new IllegalArgumentException("Could not parse [" + address + "]");
    253        }
    254    }
    255
    256    /*
    257     * Convenience method to extract the components of a dotted decimal address and
    258     * pack into an integer using a regex match
    259     */
    260    private int matchAddress(Matcher matcher) {
    261        int addr = 0;
    262        for (int i = 1; i <= 4; ++i) {
    263            int n = (rangeCheck(Integer.parseInt(matcher.group(i)), -1, 255));
    264            addr |= ((n & 0xff) << 8*(4-i));
    265        }
    266        return addr;
    267    }
    268
    269    /*
    270     * Convert a packed integer address into a 4-element array
    271     */
    272    private int[] toArray(int val) {
    273        int ret[] = new int[4];
    274        for (int j = 3; j >= 0; --j) {
    275            ret[j] |= ((val >>> 8*(3-j)) & (0xff));
    276        }
    277        return ret;
    278    }
    279
    280    /*
    281     * Convert a 4-element array into dotted decimal format
    282     */
    283    private String format(int[] octets) {
    284        StringBuilder str = new StringBuilder();
    285        for (int i =0; i < octets.length; ++i){
    286            str.append(octets[i]);
    287            if (i != octets.length - 1) {
    288                str.append(".");
    289            }
    290        }
    291        return str.toString();
    292    }
    293
    294    /*
    295     * Convenience function to check integer boundaries.
    296     * Checks if a value x is in the range (begin,end].
    297     * Returns x if it is in range, throws an exception otherwise.
    298     */
    299    private int rangeCheck(int value, int begin, int end) {
    300        if (value > begin && value <= end) { // (begin,end]
    301            return value;
    302        }
    303
    304        throw new IllegalArgumentException("Value [" + value + "] not in range ("+begin+","+end+"]");
    305    }
    306
    307    /*
    308     * Count the number of 1-bits in a 32-bit integer using a divide-and-conquer strategy
    309     * see Hacker's Delight section 5.1
    310     */
    311    int pop(int x) {
    312        x = x - ((x >>> 1) & 0x55555555);
    313        x = (x & 0x33333333) + ((x >>> 2) & 0x33333333);
    314        x = (x + (x >>> 4)) & 0x0F0F0F0F;
    315        x = x + (x >>> 8);
    316        x = x + (x >>> 16);
    317        return x & 0x0000003F;
    318    }
    319
    320    /* Convert two dotted decimal addresses to a single xxx.xxx.xxx.xxx/yy format
    321     * by counting the 1-bit population in the mask address. (It may be better to count
    322     * NBITS-#trailing zeroes for this case)
    323     */
    324    private String toCidrNotation(String addr, String mask) {
    325        return addr + "/" + pop(toInteger(mask));
    326    }
    327}