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            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    }