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;
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(final String cidrNotation) {
053      final 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          final 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(final String address, final 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(final 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(final 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(final int address) {
173            if (address == 0) { // cannot ever be in range; rejecting now avoids problems with CIDR/31,32
174                return false;
175            }
176            final long addLong = address & UNSIGNED_INT_MASK;
177            final long lowLong = low() & UNSIGNED_INT_MASK;
178            final 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            final 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            final long b = broadcastLong();
251            final long n = networkLong();
252            final long count = b - n + (isInclusiveHostCount() ? 1 : -1);
253            return count < 0 ? 0 : count;
254        }
255
256        public int asInteger(final 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            final int ct = getAddressCount();
266            final 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(final int val) {
280            final 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(final int[] octets) {
291            final 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(final String address) {
329        final Matcher matcher = addressPattern.matcher(address);
330        if (matcher.matches()) {
331            return matchAddress(matcher);
332        }
333        throw new IllegalArgumentException(String.format(PARSE_FAIL, address));
334    }
335
336    /*
337     * Convenience method to extract the components of a dotted decimal address and
338     * pack into an integer using a regex match
339     */
340    private static int matchAddress(final Matcher matcher) {
341        int addr = 0;
342        for (int i = 1; i <= 4; ++i) {
343            final int n = rangeCheck(Integer.parseInt(matcher.group(i)), 0, 255);
344            addr |= (n & 0xff) << 8*(4-i);
345        }
346        return addr;
347    }
348
349    /*
350     * Convenience function to check integer boundaries.
351     * Checks if a value x is in the range [begin,end].
352     * Returns x if it is in range, throws an exception otherwise.
353     */
354    private static int rangeCheck(final int value, final int begin, final int end) {
355        if (value >= begin && value <= end) { // (begin,end]
356            return value;
357        }
358
359        throw new IllegalArgumentException("Value [" + value + "] not in range ["+begin+","+end+"]");
360    }
361
362    /*
363     * Count the number of 1-bits in a 32-bit integer using a divide-and-conquer strategy
364     * see Hacker's Delight section 5.1
365     */
366    int pop(int x) {
367        x = x - (x >>> 1 & 0x55555555);
368        x = (x & 0x33333333) + (x >>> 2 & 0x33333333);
369        x = x + (x >>> 4) & 0x0F0F0F0F;
370        x = x + (x >>> 8);
371        x = x + (x >>> 16);
372        return x & 0x0000003F;
373    }
374
375    public SubnetUtils getNext() {
376        return new SubnetUtils(getInfo().getNextAddress(), getInfo().getNetmask());
377    }
378
379    public SubnetUtils getPrevious() {
380        return new SubnetUtils(getInfo().getPreviousAddress(), getInfo().getNetmask());
381    }
382
383}