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    /**
042     * Constructor that takes a CIDR-notation string, e.g. "192.168.0.1/16"
043     * @param cidrNotation A CIDR-notation string, e.g. "192.168.0.1/16"
044     */
045    public SubnetUtils(String cidrNotation) {
046        calculate(cidrNotation);
047    }
048
049    /**
050     * Constructor that takes two dotted decimal addresses. 
051     * @param address An IP address, e.g. "192.168.0.1"
052     * @param mask A dotted decimal netmask e.g. "255.255.0.0"
053     */
054    public SubnetUtils(String address, String mask) {
055        calculate(toCidrNotation(address, mask));
056    }
057
058    /**
059     * Convenience container for subnet summary information.
060     *
061     */
062    public final class SubnetInfo {
063        private SubnetInfo() {}
064
065        private int netmask()       { return netmask; }
066        private int network()       { return network; }
067        private int address()       { return address; }
068        private int broadcast()     { return broadcast; }
069        private int low()           { return network() + 1; }
070        private int high()          { return broadcast() - 1; }
071
072        public boolean isInRange(String address)    { return isInRange(toInteger(address)); }
073        private boolean isInRange(int address)      { return ((address-low()) <= (high()-low())); }
074
075        public String getBroadcastAddress()         { return format(toArray(broadcast())); }
076        public String getNetworkAddress()           { return format(toArray(network())); }
077        public String getNetmask()                  { return format(toArray(netmask())); }
078        public String getAddress()                  { return format(toArray(address())); }
079        public String getLowAddress()               { return format(toArray(low())); }
080        public String getHighAddress()              { return format(toArray(high())); }
081        public int getAddressCount()                { return (broadcast() - low()); }
082
083        public int asInteger(String address)        { return toInteger(address); }
084        
085        public String getCidrSignature() { 
086            return toCidrNotation(
087                    format(toArray(address())), 
088                    format(toArray(netmask()))
089            );
090        }
091        
092        public String[] getAllAddresses() { 
093            String[] addresses = new String[getAddressCount()];
094            for (int add = low(), j=0; add <= high(); ++add, ++j) {
095                addresses[j] = format(toArray(add));
096            }
097            return addresses;
098        }
099    }
100
101    /**
102     * Return a {@link SubnetInfo} instance that contains subnet-specific statistics
103     * @return
104     */
105    public final SubnetInfo getInfo() { return new SubnetInfo(); }
106
107    /*
108     * Initialize the internal fields from the supplied CIDR mask
109     */
110    private void calculate(String mask) {
111        Matcher matcher = cidrPattern.matcher(mask);
112
113        if (matcher.matches()) {
114            address = matchAddress(matcher);
115
116            /* Create a binary netmask from the number of bits specification /x */
117            int cidrPart = rangeCheck(Integer.parseInt(matcher.group(5)), 0, NBITS-1);
118            for (int j = 0; j < cidrPart; ++j) {
119                netmask |= (1 << 31-j);
120            }
121
122            /* Calculate base network address */
123            network = (address & netmask);
124
125            /* Calculate broadcast address */
126            broadcast = network | ~(netmask);
127        }
128        else 
129            throw new IllegalArgumentException("Could not parse [" + mask + "]");
130    }
131
132    /*
133     * Convert a dotted decimal format address to a packed integer format
134     */
135    private int toInteger(String address) {
136        Matcher matcher = addressPattern.matcher(address);
137        if (matcher.matches()) {
138            return matchAddress(matcher);
139        }
140        else
141            throw new IllegalArgumentException("Could not parse [" + address + "]");
142    }
143
144    /*
145     * Convenience method to extract the components of a dotted decimal address and 
146     * pack into an integer using a regex match
147     */
148    private int matchAddress(Matcher matcher) {
149        int addr = 0;
150        for (int i = 1; i <= 4; ++i) { 
151            int n = (rangeCheck(Integer.parseInt(matcher.group(i)), 0, 255));
152            addr |= ((n & 0xff) << 8*(4-i));
153        }
154        return addr;
155    }
156
157    /*
158     * Convert a packed integer address into a 4-element array
159     */
160    private int[] toArray(int val) {
161        int ret[] = new int[4];
162        for (int j = 3; j >= 0; --j)
163            ret[j] |= ((val >>> 8*(3-j)) & (0xff));
164        return ret;
165    }
166
167    /*
168     * Convert a 4-element array into dotted decimal format
169     */
170    private String format(int[] octets) {
171        StringBuilder str = new StringBuilder();
172        for (int i =0; i < octets.length; ++i){
173            str.append(octets[i]);
174            if (i != octets.length - 1) {
175                str.append("."); 
176            }
177        }
178        return str.toString();
179    }
180
181    /*
182     * Convenience function to check integer boundaries
183     */
184    private int rangeCheck(int value, int begin, int end) {
185        if (value >= begin && value <= end)
186            return value;
187
188        throw new IllegalArgumentException("Value out of range: [" + value + "]");
189    }
190
191    /*
192     * Count the number of 1-bits in a 32-bit integer using a divide-and-conquer strategy
193     * see Hacker's Delight section 5.1 
194     */
195    int pop(int x) {
196        x = x - ((x >>> 1) & 0x55555555); 
197        x = (x & 0x33333333) + ((x >>> 2) & 0x33333333); 
198        x = (x + (x >>> 4)) & 0x0F0F0F0F; 
199        x = x + (x >>> 8); 
200        x = x + (x >>> 16); 
201        return x & 0x0000003F; 
202    } 
203
204    /* Convert two dotted decimal addresses to a single xxx.xxx.xxx.xxx/yy format
205     * by counting the 1-bit population in the mask address. (It may be better to count 
206     * NBITS-#trailing zeroes for this case)
207     */
208    private String toCidrNotation(String addr, String mask) {
209        return addr + "/" + pop(toInteger(mask));
210    }
211}