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
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}