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        private int high() { 
105            return (isInclusiveHostCount() ? broadcast() :
106                broadcast() - network() > 1 ? broadcast() -1  : 0); 
107        }
108
109        /**
110         * Returns true if the parameter <code>address</code> is in the
111         * range of usable endpoint addresses for this subnet. This excludes the
112         * network and broadcast adresses.
113         * @param address A dot-delimited IPv4 address, e.g. "192.168.0.1"
114         * @return True if in range, false otherwise
115         */
116        public boolean isInRange(String address)    { return isInRange(toInteger(address)); }
117
118        private boolean isInRange(int address)      {
119            int diff = address-low();
120            return (diff >= 0 && (diff <= (high()-low())));
121        }
122
123        public String getBroadcastAddress()         { return format(toArray(broadcast())); }
124        public String getNetworkAddress()           { return format(toArray(network())); }
125        public String getNetmask()                  { return format(toArray(netmask())); }
126        public String getAddress()                  { return format(toArray(address())); }
127
128        /**
129         * Return the low address as a dotted IP address.
130         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
131         * 
132         * @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
133         */
134        public String getLowAddress()               { return format(toArray(low())); }
135
136        /**
137         * Return the high address as a dotted IP address.
138         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
139         * 
140         * @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
141         */
142        public String getHighAddress()              { return format(toArray(high())); }
143        
144        /**
145         * Get the count of available addresses.
146         * Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
147         * @return the count of addresses, may be zero.
148         */
149        public int getAddressCount()                { 
150            int count = broadcast() - network() + (isInclusiveHostCount() ? 1 : -1);
151            return count < 0 ? 0 : count;
152        }
153
154        public int asInteger(String address)        { return toInteger(address); }
155
156        public String getCidrSignature() {
157            return toCidrNotation(
158                    format(toArray(address())),
159                    format(toArray(netmask()))
160            );
161        }
162
163        public String[] getAllAddresses() {
164            int ct = getAddressCount();
165            String[] addresses = new String[ct];
166            if (ct == 0) {
167                return addresses;
168            }
169            for (int add = low(), j=0; add <= high(); ++add, ++j) {
170                addresses[j] = format(toArray(add));
171            }
172            return addresses;
173        }
174
175        /**
176         * {@inheritDoc}
177         * @since 2.2
178         */
179        @Override
180        public String toString() {
181            final StringBuilder buf = new StringBuilder();
182            buf.append("CIDR Signature:\t[").append(getCidrSignature()).append("]")
183                .append(" Netmask: [").append(getNetmask()).append("]\n")
184                .append("Network:\t[").append(getNetworkAddress()).append("]\n")
185                .append("Broadcast:\t[").append(getBroadcastAddress()).append("]\n")
186                 .append("First Address:\t[").append(getLowAddress()).append("]\n")
187                 .append("Last Address:\t[").append(getHighAddress()).append("]\n")
188                 .append("# Addresses:\t[").append(getAddressCount()).append("]\n");
189            return buf.toString();
190        }
191    }
192
193    /**
194     * Return a {@link SubnetInfo} instance that contains subnet-specific statistics
195     * @return new instance
196     */
197    public final SubnetInfo getInfo() { return new SubnetInfo(); }
198
199    /*
200     * Initialize the internal fields from the supplied CIDR mask
201     */
202    private void calculate(String mask) {
203        Matcher matcher = cidrPattern.matcher(mask);
204
205        if (matcher.matches()) {
206            address = matchAddress(matcher);
207
208            /* Create a binary netmask from the number of bits specification /x */
209            int cidrPart = rangeCheck(Integer.parseInt(matcher.group(5)), 0, NBITS);
210            for (int j = 0; j < cidrPart; ++j) {
211                netmask |= (1 << 31-j);
212            }
213
214            /* Calculate base network address */
215            network = (address & netmask);
216
217            /* Calculate broadcast address */
218            broadcast = network | ~(netmask);
219        } else {
220            throw new IllegalArgumentException("Could not parse [" + mask + "]");
221        }
222    }
223
224    /*
225     * Convert a dotted decimal format address to a packed integer format
226     */
227    private int toInteger(String address) {
228        Matcher matcher = addressPattern.matcher(address);
229        if (matcher.matches()) {
230            return matchAddress(matcher);
231        } else {
232            throw new IllegalArgumentException("Could not parse [" + address + "]");
233        }
234    }
235
236    /*
237     * Convenience method to extract the components of a dotted decimal address and
238     * pack into an integer using a regex match
239     */
240    private int matchAddress(Matcher matcher) {
241        int addr = 0;
242        for (int i = 1; i <= 4; ++i) {
243            int n = (rangeCheck(Integer.parseInt(matcher.group(i)), -1, 255));
244            addr |= ((n & 0xff) << 8*(4-i));
245        }
246        return addr;
247    }
248
249    /*
250     * Convert a packed integer address into a 4-element array
251     */
252    private int[] toArray(int val) {
253        int ret[] = new int[4];
254        for (int j = 3; j >= 0; --j) {
255            ret[j] |= ((val >>> 8*(3-j)) & (0xff));
256        }
257        return ret;
258    }
259
260    /*
261     * Convert a 4-element array into dotted decimal format
262     */
263    private String format(int[] octets) {
264        StringBuilder str = new StringBuilder();
265        for (int i =0; i < octets.length; ++i){
266            str.append(octets[i]);
267            if (i != octets.length - 1) {
268                str.append(".");
269            }
270        }
271        return str.toString();
272    }
273
274    /*
275     * Convenience function to check integer boundaries.
276     * Checks if a value x is in the range (begin,end].
277     * Returns x if it is in range, throws an exception otherwise.
278     */
279    private int rangeCheck(int value, int begin, int end) {
280        if (value > begin && value <= end) { // (begin,end]
281            return value;
282        }
283
284        throw new IllegalArgumentException("Value [" + value + "] not in range ("+begin+","+end+"]");
285    }
286
287    /*
288     * Count the number of 1-bits in a 32-bit integer using a divide-and-conquer strategy
289     * see Hacker's Delight section 5.1
290     */
291    int pop(int x) {
292        x = x - ((x >>> 1) & 0x55555555);
293        x = (x & 0x33333333) + ((x >>> 2) & 0x33333333);
294        x = (x + (x >>> 4)) & 0x0F0F0F0F;
295        x = x + (x >>> 8);
296        x = x + (x >>> 16);
297        return x & 0x0000003F;
298    }
299
300    /* Convert two dotted decimal addresses to a single xxx.xxx.xxx.xxx/yy format
301     * by counting the 1-bit population in the mask address. (It may be better to count
302     * NBITS-#trailing zeroes for this case)
303     */
304    private String toCidrNotation(String addr, String mask) {
305        return addr + "/" + pop(toInteger(mask));
306    }
307}