    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     */
    017    package org.apache.commons.net.util;
    018
    019    import java.util.regex.Matcher;
    020    import 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     */
    028    public 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            private int low()           { return network() + (isInclusiveHostCount() ? 0 : 1); }
    100            private int high()          { return broadcast() - (isInclusiveHostCount() ? 0 : 1); }
    101
    102            /**
    103             * Returns true if the parameter <code>address</code> is in the
    104             * range of usable endpoint addresses for this subnet. This excludes the
    105             * network and broadcast adresses.
    106             * @param address A dot-delimited IPv4 address, e.g. "192.168.0.1"
    107             * @return True if in range, false otherwise
    108             */
    109            public boolean isInRange(String address)    { return isInRange(toInteger(address)); }
    110
    111            private boolean isInRange(int address)      {
    112                int diff = address-low();
    113                return (diff >= 0 && (diff <= (high()-low())));
    114            }
    115
    116            public String getBroadcastAddress()         { return format(toArray(broadcast())); }
    117            public String getNetworkAddress()           { return format(toArray(network())); }
    118            public String getNetmask()                  { return format(toArray(netmask())); }
    119            public String getAddress()                  { return format(toArray(address())); }
    120            public String getLowAddress()               { return format(toArray(low())); }
    121            public String getHighAddress()              { return format(toArray(high())); }
    122            public int getAddressCount()                { return (broadcast() - low() + (isInclusiveHostCount() ? 1 : 0)); }
    123
    124            public int asInteger(String address)        { return toInteger(address); }
    125
    126            public String getCidrSignature() {
    127                return toCidrNotation(
    128                        format(toArray(address())),
    129                        format(toArray(netmask()))
    130                );
    131            }
    132
    133            public String[] getAllAddresses() {
    134                String[] addresses = new String[getAddressCount()];
    135                for (int add = low(), j=0; add <= high(); ++add, ++j) {
    136                    addresses[j] = format(toArray(add));
    137                }
    138                return addresses;
    139            }
    140
    141            /**
    142             * {@inheritDoc}
    143             * @since 2.2
    144             */
    145            @Override
    146            public String toString() {
    147                final StringBuilder buf = new StringBuilder();
    148                buf.append("CIDR Signature:\t[").append(getCidrSignature()).append("]")
    149                    .append(" Netmask: [").append(getNetmask()).append("]\n")
    150                    .append("Network:\t[").append(getNetworkAddress()).append("]\n")
    151                    .append("Broadcast:\t[").append(getBroadcastAddress()).append("]\n")
    152                     .append("First Address:\t[").append(getLowAddress()).append("]\n")
    153                     .append("Last Address:\t[").append(getHighAddress()).append("]\n")
    154                     .append("# Addresses:\t[").append(getAddressCount()).append("]\n");
    155                return buf.toString();
    156            }
    157        }
    158
    159        /**
    160         * Return a {@link SubnetInfo} instance that contains subnet-specific statistics
    161         * @return new instance
    162         */
    163        public final SubnetInfo getInfo() { return new SubnetInfo(); }
    164
    165        /*
    166         * Initialize the internal fields from the supplied CIDR mask
    167         */
    168        private void calculate(String mask) {
    169            Matcher matcher = cidrPattern.matcher(mask);
    170
    171            if (matcher.matches()) {
    172                address = matchAddress(matcher);
    173
    174                /* Create a binary netmask from the number of bits specification /x */
    175                int cidrPart = rangeCheck(Integer.parseInt(matcher.group(5)), -1, NBITS);
    176                for (int j = 0; j < cidrPart; ++j) {
    177                    netmask |= (1 << 31-j);
    178                }
    179
    180                rangeCheck(pop(netmask),0, NBITS);
    181
    182                /* Calculate base network address */
    183                network = (address & netmask);
    184
    185                /* Calculate broadcast address */
    186                broadcast = network | ~(netmask);
    187            }
    188            else
    189                throw new IllegalArgumentException("Could not parse [" + mask + "]");
    190        }
    191
    192        /*
    193         * Convert a dotted decimal format address to a packed integer format
    194         */
    195        private int toInteger(String address) {
    196            Matcher matcher = addressPattern.matcher(address);
    197            if (matcher.matches()) {
    198                return matchAddress(matcher);
    199            }
    200            else
    201                throw new IllegalArgumentException("Could not parse [" + address + "]");
    202        }
    203
    204        /*
    205         * Convenience method to extract the components of a dotted decimal address and
    206         * pack into an integer using a regex match
    207         */
    208        private int matchAddress(Matcher matcher) {
    209            int addr = 0;
    210            for (int i = 1; i <= 4; ++i) {
    211                int n = (rangeCheck(Integer.parseInt(matcher.group(i)), -1, 255));
    212                addr |= ((n & 0xff) << 8*(4-i));
    213            }
    214            return addr;
    215        }
    216
    217        /*
    218         * Convert a packed integer address into a 4-element array
    219         */
    220        private int[] toArray(int val) {
    221            int ret[] = new int[4];
    222            for (int j = 3; j >= 0; --j)
    223                ret[j] |= ((val >>> 8*(3-j)) & (0xff));
    224            return ret;
    225        }
    226
    227        /*
    228         * Convert a 4-element array into dotted decimal format
    229         */
    230        private String format(int[] octets) {
    231            StringBuilder str = new StringBuilder();
    232            for (int i =0; i < octets.length; ++i){
    233                str.append(octets[i]);
    234                if (i != octets.length - 1) {
    235                    str.append(".");
    236                }
    237            }
    238            return str.toString();
    239        }
    240
    241        /*
    242         * Convenience function to check integer boundaries.
    243         * Checks if a value x is in the range (begin,end].
    244         * Returns x if it is in range, throws an exception otherwise.
    245         */
    246        private int rangeCheck(int value, int begin, int end) {
    247            if (value > begin && value <= end) // (begin,end]
    248                return value;
    249
    250            throw new IllegalArgumentException("Value [" + value + "] not in range ("+begin+","+end+"]");
    251        }
    252
    253        /*
    254         * Count the number of 1-bits in a 32-bit integer using a divide-and-conquer strategy
    255         * see Hacker's Delight section 5.1
    256         */
    257        int pop(int x) {
    258            x = x - ((x >>> 1) & 0x55555555);
    259            x = (x & 0x33333333) + ((x >>> 2) & 0x33333333);
    260            x = (x + (x >>> 4)) & 0x0F0F0F0F;
    261            x = x + (x >>> 8);
    262            x = x + (x >>> 16);
    263            return x & 0x0000003F;
    264        }
    265
    266        /* Convert two dotted decimal addresses to a single xxx.xxx.xxx.xxx/yy format
    267         * by counting the 1-bit population in the mask address. (It may be better to count
    268         * NBITS-#trailing zeroes for this case)
    269         */
    270        private String toCidrNotation(String addr, String mask) {
    271            return addr + "/" + pop(toInteger(mask));
    272        }
    273    }