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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.net.util;
18  
19  import java.util.regex.Matcher;
20  import java.util.regex.Pattern;
21  
22  /**
23   * A class that performs some subnet calculations given a network address and a subnet mask.
24   * @see "http://www.faqs.org/rfcs/rfc1519.html"
25   * @author <rwinston@apache.org>
26   * @since 2.0
27   */
28  public class SubnetUtils {
29  
30      private static final String IP_ADDRESS = "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})";
31      private static final String SLASH_FORMAT = IP_ADDRESS + "/(\\d{1,3})";
32      private static final Pattern addressPattern = Pattern.compile(IP_ADDRESS);
33      private static final Pattern cidrPattern = Pattern.compile(SLASH_FORMAT);
34      private static final int NBITS = 32;
35  
36      private int netmask = 0;
37      private int address = 0;
38      private int network = 0;
39      private int broadcast = 0;
40  
41      /** Whether the broadcast/network address are included in host count */
42      private boolean inclusiveHostCount = false;
43  
44  
45      /**
46       * Constructor that takes a CIDR-notation string, e.g. "192.168.0.1/16"
47       * @param cidrNotation A CIDR-notation string, e.g. "192.168.0.1/16"
48       * @throws IllegalArgumentException if the parameter is invalid,
49       * 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
50       */
51      public SubnetUtils(String cidrNotation) {
52          calculate(cidrNotation);
53      }
54  
55      /**
56       * Constructor that takes a dotted decimal address and a dotted decimal mask.
57       * @param address An IP address, e.g. "192.168.0.1"
58       * @param mask A dotted decimal netmask e.g. "255.255.0.0"
59       * @throws IllegalArgumentException if the address or mask is invalid,
60       * i.e. does not match n.n.n.n where n=1-3 decimal digits and the mask is not all zeros
61       */
62      public SubnetUtils(String address, String mask) {
63          calculate(toCidrNotation(address, mask));
64      }
65  
66  
67      /**
68       * Returns <code>true</code> if the return value of {@link SubnetInfo#getAddressCount()}
69       * includes the network address and broadcast addresses.
70       * @since 2.2
71       */
72      public boolean isInclusiveHostCount() {
73          return inclusiveHostCount;
74      }
75  
76      /**
77       * Set to <code>true</code> if you want the return value of {@link SubnetInfo#getAddressCount()}
78       * to include the network and broadcast addresses.
79       * @param inclusiveHostCount
80       * @since 2.2
81       */
82      public void setInclusiveHostCount(boolean inclusiveHostCount) {
83          this.inclusiveHostCount = inclusiveHostCount;
84      }
85  
86  
87  
88      /**
89       * Convenience container for subnet summary information.
90       *
91       */
92      public final class SubnetInfo {
93          private SubnetInfo() {}
94  
95          private int netmask()       { return netmask; }
96          private int network()       { return network; }
97          private int address()       { return address; }
98          private int broadcast()     { return broadcast; }
99  
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 }