    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
    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    }