    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 * @since 2.0
    026 */
    027public class SubnetUtils {
    028
    029    private static final String IP_ADDRESS = "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})";
    030    private static final String SLASH_FORMAT = IP_ADDRESS + "/(\\d{1,2})"; // 0 -> 32
    031    private static final Pattern addressPattern = Pattern.compile(IP_ADDRESS);
    032    private static final Pattern cidrPattern = Pattern.compile(SLASH_FORMAT);
    033    private static final int NBITS = 32;
    034
    035    private static final String PARSE_FAIL = "Could not parse [%s]";
    036
    037    private final int netmask;
    038    private final int address;
    039    private final int network;
    040    private final int broadcast;
    041
    042    /** Whether the broadcast/network address are included in host count */
    043    private boolean inclusiveHostCount = false;
    044
    045
    046    /**
    047     * Constructor that takes a CIDR-notation string, e.g. "192.168.0.1/16"
    048     * @param cidrNotation A CIDR-notation string, e.g. "192.168.0.1/16"
    049     * @throws IllegalArgumentException if the parameter is invalid,
    050     * i.e. does not match n.n.n.n/m where n=1-3 decimal digits, m = 1-2 decimal digits in range 0-32
    051     */
    052    public SubnetUtils(String cidrNotation) {
    053      Matcher matcher = cidrPattern.matcher(cidrNotation);
    054
    055      if (matcher.matches()) {
    056          this.address = matchAddress(matcher);
    057
    058          /* Create a binary netmask from the number of bits specification /x */
    059
    060          int trailingZeroes = NBITS - rangeCheck(Integer.parseInt(matcher.group(5)), 0, NBITS);
    061          /*
    062           * An IPv4 netmask consists of 32 bits, a contiguous sequence
    063           * of the specified number of ones followed by all zeros.
    064           * So, it can be obtained by shifting an unsigned integer (32 bits) to the left by
    065           * the number of trailing zeros which is (32 - the # bits specification).
    066           * Note that there is no unsigned left shift operator, so we have to use
    067           * a long to ensure that the left-most bit is shifted out correctly.
    068           */
    069          this.netmask = (int) (0x0FFFFFFFFL << trailingZeroes );
    070
    071          /* Calculate base network address */
    072          this.network = (address & netmask);
    073
    074          /* Calculate broadcast address */
    075          this.broadcast = network | ~(netmask);
    076      } else {
    077          throw new IllegalArgumentException(String.format(PARSE_FAIL, cidrNotation));
    078      }
    079    }
    080
    081    /**
    082     * Constructor that takes a dotted decimal address and a dotted decimal mask.
    083     * @param address An IP address, e.g. "192.168.0.1"
    084     * @param mask A dotted decimal netmask e.g. "255.255.0.0"
    085     * @throws IllegalArgumentException if the address or mask is invalid,
    086     * i.e. does not match n.n.n.n where n=1-3 decimal digits and the mask is not all zeros
    087     */
    088    public SubnetUtils(String address, String mask) {
    089        this.address = toInteger(address);
    090        this.netmask = toInteger(mask);
    091
    092        if ((this.netmask & -this.netmask) - 1 != ~this.netmask) {
    093            throw new IllegalArgumentException(String.format(PARSE_FAIL, mask));
    094        }
    095
    096        /* Calculate base network address */
    097        this.network = (this.address & this.netmask);
    098
    099        /* Calculate broadcast address */
    100        this.broadcast = this.network | ~(this.netmask);
    101    }
    102
    103
    104    /**
    105     * Returns <code>true</code> if the return value of {@link SubnetInfo#getAddressCount()}
    106     * includes the network and broadcast addresses.
    107     * @since 2.2
    108     * @return true if the host count includes the network and broadcast addresses
    109     */
    110    public boolean isInclusiveHostCount() {
    111        return inclusiveHostCount;
    112    }
    113
    114    /**
    115     * Set to <code>true</code> if you want the return value of {@link SubnetInfo#getAddressCount()}
    116     * to include the network and broadcast addresses.
    117     * This also applies to {@link SubnetInfo#isInRange(int)}
    118     * @param inclusiveHostCount true if network and broadcast addresses are to be included
    119     * @since 2.2
    120     */
    121    public void setInclusiveHostCount(boolean inclusiveHostCount) {
    122        this.inclusiveHostCount = inclusiveHostCount;
    123    }
    124
    125
    126
    127    /**
    128     * Convenience container for subnet summary information.
    129     *
    130     */
    131    public final class SubnetInfo {
    132        /* Mask to convert unsigned int to a long (i.e. keep 32 bits) */
    133        private static final long UNSIGNED_INT_MASK = 0x0FFFFFFFFL;
    134
    135        private SubnetInfo() {}
    136
    137        // long versions of the values (as unsigned int) which are more suitable for range checking
    138        private long networkLong()  { return network &  UNSIGNED_INT_MASK; }
    139        private long broadcastLong(){ return broadcast &  UNSIGNED_INT_MASK; }
    140
    141        private int low() {
    142            return (isInclusiveHostCount() ? network :
    143                broadcastLong() - networkLong() > 1 ? network + 1 : 0);
    144        }
    145
    146        private int high() {
    147            return (isInclusiveHostCount() ? broadcast :
    148                broadcastLong() - networkLong() > 1 ? broadcast -1  : 0);
    149        }
    150
    151        /**
    152         * Returns true if the parameter <code>address</code> is in the
    153         * range of usable endpoint addresses for this subnet. This excludes the
    154         * network and broadcast addresses. Use {@link SubnetUtils#setInclusiveHostCount(boolean)}
    155         * to change this.
    156         * @param address A dot-delimited IPv4 address, e.g. "192.168.0.1"
    157         * @return True if in range, false otherwise
    158         */
    159        public boolean isInRange(String address) {
    160            return isInRange(toInteger(address));
    161        }
    162
    163        /**
    164         * Returns true if the parameter <code>address</code> is in the
    165         * range of usable endpoint addresses for this subnet. This excludes the
    166         * network and broadcast addresses by default. Use {@link SubnetUtils#setInclusiveHostCount(boolean)}
    167         * to change this.
    168         * @param address the address to check
    169         * @return true if it is in range
    170         * @since 3.4 (made public)
    171         */
    172        public boolean isInRange(int address) {
    173            if (address == 0) { // cannot ever be in range; rejecting now avoids problems with CIDR/31,32
    174                return false;
    175            }
    176            long addLong = address & UNSIGNED_INT_MASK;
    177            long lowLong = low() & UNSIGNED_INT_MASK;
    178            long highLong = high() & UNSIGNED_INT_MASK;
    179            return addLong >= lowLong && addLong <= highLong;
    180        }
    181
    182        public String getBroadcastAddress() {
    183            return format(toArray(broadcast));
    184        }
    185
    186        public String getNetworkAddress() {
    187            return format(toArray(network));
    188        }
    189
    190        public String getNetmask() {
    191            return format(toArray(netmask));
    192        }
    193
    194        public String getAddress() {
    195            return format(toArray(address));
    196        }
    197
    198        public String getNextAddress() {
    199            return format(toArray(address + 1));
    200        }
    201
    202        public String getPreviousAddress() {
    203            return format(toArray(address - 1));
    204        }
    205
    206        /**
    207         * Return the low address as a dotted IP address.
    208         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
    209         *
    210         * @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
    211         */
    212        public String getLowAddress() {
    213            return format(toArray(low()));
    214        }
    215
    216        /**
    217         * Return the high address as a dotted IP address.
    218         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
    219         *
    220         * @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
    221         */
    222        public String getHighAddress() {
    223            return format(toArray(high()));
    224        }
    225
    226        /**
    227         * Get the count of available addresses.
    228         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
    229         * @return the count of addresses, may be zero.
    230         * @throws RuntimeException if the correct count is greater than {@code Integer.MAX_VALUE}
    231         * @deprecated (3.4) use {@link #getAddressCountLong()} instead
    232         */
    233        @Deprecated
    234        public int getAddressCount() {
    235            long countLong = getAddressCountLong();
    236            if (countLong > Integer.MAX_VALUE) {
    237                throw new RuntimeException("Count is larger than an integer: " + countLong);
    238            }
    239            // N.B. cannot be negative
    240            return (int)countLong;
    241        }
    242
    243        /**
    244         * Get the count of available addresses.
    245         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
    246         * @return the count of addresses, may be zero.
    247         * @since 3.4
    248         */
    249        public long getAddressCountLong() {
    250            long b = broadcastLong();
    251            long n = networkLong();
    252            long count = b - n + (isInclusiveHostCount() ? 1 : -1);
    253            return count < 0 ? 0 : count;
    254        }
    255
    256        public int asInteger(String address) {
    257            return toInteger(address);
    258        }
    259
    260        public String getCidrSignature() {
    261            return format(toArray(address)) + "/" + pop(netmask);
    262        }
    263
    264        public String[] getAllAddresses() {
    265            int ct = getAddressCount();
    266            String[] addresses = new String[ct];
    267            if (ct == 0) {
    268                return addresses;
    269            }
    270            for (int add = low(), j=0; add <= high(); ++add, ++j) {
    271                addresses[j] = format(toArray(add));
    272            }
    273            return addresses;
    274        }
    275
    276        /*
    277        * Convert a packed integer address into a 4-element array
    278        */
    279        private int[] toArray(int val) {
    280            int ret[] = new int[4];
    281            for (int j = 3; j >= 0; --j) {
    282                ret[j] |= ((val >>> 8*(3-j)) & (0xff));
    283            }
    284            return ret;
    285        }
    286
    287        /*
    288        * Convert a 4-element array into dotted decimal format
    289        */
    290        private String format(int[] octets) {
    291            StringBuilder str = new StringBuilder();
    292            for (int i =0; i < octets.length; ++i){
    293                str.append(octets[i]);
    294                if (i != octets.length - 1) {
    295                    str.append(".");
    296                }
    297            }
    298            return str.toString();
    299        }
    300
    301        /**
    302         * {@inheritDoc}
    303         * @since 2.2
    304         */
    305        @Override
    306        public String toString() {
    307            final StringBuilder buf = new StringBuilder();
    308            buf.append("CIDR Signature:\t[").append(getCidrSignature()).append("]")
    309                .append(" Netmask: [").append(getNetmask()).append("]\n")
    310                .append("Network:\t[").append(getNetworkAddress()).append("]\n")
    311                .append("Broadcast:\t[").append(getBroadcastAddress()).append("]\n")
    312                 .append("First Address:\t[").append(getLowAddress()).append("]\n")
    313                 .append("Last Address:\t[").append(getHighAddress()).append("]\n")
    314                 .append("# Addresses:\t[").append(getAddressCount()).append("]\n");
    315            return buf.toString();
    316        }
    317    }
    318
    319    /**
    320     * Return a {@link SubnetInfo} instance that contains subnet-specific statistics
    321     * @return new instance
    322     */
    323    public final SubnetInfo getInfo() { return new SubnetInfo(); }
    324
    325    /*
    326     * Convert a dotted decimal format address to a packed integer format
    327     */
    328    private static int toInteger(String address) {
    329        Matcher matcher = addressPattern.matcher(address);
    330        if (matcher.matches()) {
    331            return matchAddress(matcher);
    332        } else {
    333            throw new IllegalArgumentException(String.format(PARSE_FAIL, address));
    334        }
    335    }
    336
    337    /*
    338     * Convenience method to extract the components of a dotted decimal address and
    339     * pack into an integer using a regex match
    340     */
    341    private static int matchAddress(Matcher matcher) {
    342        int addr = 0;
    343        for (int i = 1; i <= 4; ++i) {
    344            int n = (rangeCheck(Integer.parseInt(matcher.group(i)), 0, 255));
    345            addr |= ((n & 0xff) << 8*(4-i));
    346        }
    347        return addr;
    348    }
    349
    350    /*
    351     * Convenience function to check integer boundaries.
    352     * Checks if a value x is in the range [begin,end].
    353     * Returns x if it is in range, throws an exception otherwise.
    354     */
    355    private static int rangeCheck(int value, int begin, int end) {
    356        if (value >= begin && value <= end) { // (begin,end]
    357            return value;
    358        }
    359
    360        throw new IllegalArgumentException("Value [" + value + "] not in range ["+begin+","+end+"]");
    361    }
    362
    363    /*
    364     * Count the number of 1-bits in a 32-bit integer using a divide-and-conquer strategy
    365     * see Hacker's Delight section 5.1
    366     */
    367    int pop(int x) {
    368        x = x - ((x >>> 1) & 0x55555555);
    369        x = (x & 0x33333333) + ((x >>> 2) & 0x33333333);
    370        x = (x + (x >>> 4)) & 0x0F0F0F0F;
    371        x = x + (x >>> 8);
    372        x = x + (x >>> 16);
    373        return x & 0x0000003F;
    374    }
    375
    376    public SubnetUtils getNext() {
    377        return new SubnetUtils(getInfo().getNextAddress(), getInfo().getNetmask());
    378    }
    379
    380    public SubnetUtils getPrevious() {
    381        return new SubnetUtils(getInfo().getPreviousAddress(), getInfo().getNetmask());
    382    }
    383
    384}