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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   * Performs some subnet calculations given a network address and a subnet mask.
24   *
25   * @see "http://www.faqs.org/rfcs/rfc1519.html"
26   * @since 2.0
27   */
28  public class SubnetUtils {
29  
30      /**
31       * Convenience container for subnet summary information.
32       */
33      public final class SubnetInfo {
34  
35          /** Mask to convert unsigned int to a long (i.e. keep 32 bits). */
36          private static final long UNSIGNED_INT_MASK = 0x0FFFFFFFFL;
37  
38          private SubnetInfo() {
39          }
40  
41          public int asInteger(final String address) {
42              return toInteger(address);
43          }
44  
45          private long broadcastLong() {
46              return broadcast & UNSIGNED_INT_MASK;
47          }
48  
49          /**
50           * Converts a 4-element array into dotted decimal format.
51           */
52          private String format(final int[] octets) {
53              final int last = octets.length - 1;
54              final StringBuilder builder = new StringBuilder();
55              for (int i = 0;; i++) {
56                  builder.append(octets[i]);
57                  if (i == last) {
58                      return builder.toString();
59                  }
60                  builder.append('.');
61              }
62          }
63  
64          public String getAddress() {
65              return format(toArray(address));
66          }
67  
68          /**
69           * Gets the count of available addresses. Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
70           *
71           * @return the count of addresses, may be zero.
72           * @throws RuntimeException if the correct count is greater than {@code Integer.MAX_VALUE}
73           * @deprecated (3.4) use {@link #getAddressCountLong()} instead
74           */
75          @Deprecated
76          public int getAddressCount() {
77              final long countLong = getAddressCountLong();
78              if (countLong > Integer.MAX_VALUE) {
79                  throw new RuntimeException("Count is larger than an integer: " + countLong);
80              }
81              // Cannot be negative here
82              return (int) countLong;
83          }
84  
85          /**
86           * Gets the count of available addresses. Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
87           *
88           * @return the count of addresses, may be zero.
89           * @since 3.4
90           */
91          public long getAddressCountLong() {
92              final long b = broadcastLong();
93              final long n = networkLong();
94              final long count = b - n + (isInclusiveHostCount() ? 1 : -1);
95              return count < 0 ? 0 : count;
96          }
97  
98          public String[] getAllAddresses() {
99              final int ct = getAddressCount();
100             final String[] addresses = new String[ct];
101             if (ct == 0) {
102                 return addresses;
103             }
104             for (int add = low(), j = 0; add <= high(); ++add, ++j) {
105                 addresses[j] = format(toArray(add));
106             }
107             return addresses;
108         }
109 
110         public String getBroadcastAddress() {
111             return format(toArray(broadcast));
112         }
113 
114         public String getCidrSignature() {
115             return format(toArray(address)) + "/" + Integer.bitCount(netmask);
116         }
117 
118         /**
119          * Gets the high address as a dotted IP address. Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
120          *
121          * @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
122          */
123         public String getHighAddress() {
124             return format(toArray(high()));
125         }
126 
127         /**
128          * Gets the low address as a dotted IP address. Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
129          *
130          * @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
131          */
132         public String getLowAddress() {
133             return format(toArray(low()));
134         }
135 
136         public String getNetmask() {
137             return format(toArray(netmask));
138         }
139 
140         public String getNetworkAddress() {
141             return format(toArray(network));
142         }
143 
144         public String getNextAddress() {
145             return format(toArray(address + 1));
146         }
147 
148         public String getPreviousAddress() {
149             return format(toArray(address - 1));
150         }
151 
152         private int high() {
153             return isInclusiveHostCount() ? broadcast : broadcastLong() - networkLong() > 1 ? broadcast - 1 : 0;
154         }
155 
156         /**
157          * Tests if the parameter <code>address</code> is in the range of usable endpoint addresses for this subnet. This excludes the network and broadcast
158          * addresses by default. Use {@link SubnetUtils#setInclusiveHostCount(boolean)} to change this.
159          *
160          * @param address the address to check
161          * @return true if it is in range
162          * @since 3.4 (made public)
163          */
164         public boolean isInRange(final int address) {
165             if (address == 0) { // cannot ever be in range; rejecting now avoids problems with CIDR/31,32
166                 return false;
167             }
168             final long addLong = address & UNSIGNED_INT_MASK;
169             final long lowLong = low() & UNSIGNED_INT_MASK;
170             final long highLong = high() & UNSIGNED_INT_MASK;
171             return addLong >= lowLong && addLong <= highLong;
172         }
173 
174         /**
175          * Tests if the parameter <code>address</code> is in the range of usable endpoint addresses for this subnet. This excludes the network and broadcast
176          * addresses. Use {@link SubnetUtils#setInclusiveHostCount(boolean)} to change this.
177          *
178          * @param address A dot-delimited IPv4 address, e.g. "192.168.0.1"
179          * @return True if in range, false otherwise
180          */
181         public boolean isInRange(final String address) {
182             return isInRange(toInteger(address));
183         }
184 
185         private int low() {
186             return isInclusiveHostCount() ? network : broadcastLong() - networkLong() > 1 ? network + 1 : 0;
187         }
188 
189         /** long versions of the values (as unsigned int) which are more suitable for range checking. */
190         private long networkLong() {
191             return network & UNSIGNED_INT_MASK;
192         }
193 
194         /**
195          * Converts a packed integer address into a 4-element array
196          */
197         private int[] toArray(final int val) {
198             final int ret[] = new int[4];
199             for (int j = 3; j >= 0; --j) {
200                 ret[j] |= val >>> 8 * (3 - j) & 0xff;
201             }
202             return ret;
203         }
204 
205         /**
206          * {@inheritDoc}
207          *
208          * @since 2.2
209          */
210         @Override
211         public String toString() {
212             final StringBuilder buf = new StringBuilder();
213             // @formatter:off
214             buf.append("CIDR Signature:\t[").append(getCidrSignature()).append("]\n")
215                 .append("  Netmask: [").append(getNetmask()).append("]\n")
216                 .append("  Network: [").append(getNetworkAddress()).append("]\n")
217                 .append("  Broadcast: [").append(getBroadcastAddress()).append("]\n")
218                 .append("  First address: [").append(getLowAddress()).append("]\n")
219                 .append("  Last address: [").append(getHighAddress()).append("]\n")
220                 .append("  Address Count: [").append(getAddressCountLong()).append("]\n");
221             // @formatter:on
222             return buf.toString();
223         }
224     }
225 
226     private static final String IP_ADDRESS = "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})";
227     private static final String SLASH_FORMAT = IP_ADDRESS + "/(\\d{1,2})"; // 0 -> 32
228     private static final Pattern ADDRESS_PATTERN = Pattern.compile(IP_ADDRESS);
229     private static final Pattern CIDR_PATTERN = Pattern.compile(SLASH_FORMAT);
230 
231     private static final int NBITS = 32;
232 
233     private static final String PARSE_FAIL = "Could not parse [%s]";
234 
235     /*
236      * Extracts the components of a dotted decimal address and pack into an integer using a regex match
237      */
238     private static int matchAddress(final Matcher matcher) {
239         int addr = 0;
240         for (int i = 1; i <= 4; ++i) {
241             final int n = rangeCheck(Integer.parseInt(matcher.group(i)), 0, 255);
242             addr |= (n & 0xff) << 8 * (4 - i);
243         }
244         return addr;
245     }
246 
247     /*
248      * Checks integer boundaries. Checks if a value x is in the range [begin,end]. Returns x if it is in range, throws an exception otherwise.
249      */
250     private static int rangeCheck(final int value, final int begin, final int end) {
251         if (value >= begin && value <= end) { // (begin,end]
252             return value;
253         }
254         throw new IllegalArgumentException("Value [" + value + "] not in range [" + begin + "," + end + "]");
255     }
256 
257     /*
258      * Converts a dotted decimal format address to a packed integer format
259      */
260     private static int toInteger(final String address) {
261         final Matcher matcher = ADDRESS_PATTERN.matcher(address);
262         if (matcher.matches()) {
263             return matchAddress(matcher);
264         }
265         throw new IllegalArgumentException(String.format(PARSE_FAIL, address));
266     }
267 
268     private final int netmask;
269 
270     private final int address;
271 
272     private final int network;
273 
274     private final int broadcast;
275 
276     /** Whether the broadcast/network address are included in host count */
277     private boolean inclusiveHostCount;
278 
279     /**
280      * Constructs an instance from a CIDR-notation string, e.g. "192.168.0.1/16"
281      *
282      * @param cidrNotation A CIDR-notation string, e.g. "192.168.0.1/16"
283      * @throws IllegalArgumentException if the parameter is invalid, i.e. does not match n.n.n.n/m where n=1-3 decimal digits, m = 1-2 decimal digits in range
284      *                                  0-32
285      */
286     public SubnetUtils(final String cidrNotation) {
287         final Matcher matcher = CIDR_PATTERN.matcher(cidrNotation);
288 
289         if (!matcher.matches()) {
290             throw new IllegalArgumentException(String.format(PARSE_FAIL, cidrNotation));
291         }
292         this.address = matchAddress(matcher);
293 
294         // Create a binary netmask from the number of bits specification /x
295 
296         final int trailingZeroes = NBITS - rangeCheck(Integer.parseInt(matcher.group(5)), 0, NBITS);
297 
298         //
299         // An IPv4 netmask consists of 32 bits, a contiguous sequence
300         // of the specified number of ones followed by all zeros.
301         // So, it can be obtained by shifting an unsigned integer (32 bits) to the left by
302         // the number of trailing zeros which is (32 - the # bits specification).
303         // Note that there is no unsigned left shift operator, so we have to use
304         // a long to ensure that the left-most bit is shifted out correctly.
305         //
306         this.netmask = (int) (0x0FFFFFFFFL << trailingZeroes);
307 
308         // Calculate base network address
309         this.network = address & netmask;
310 
311         // Calculate broadcast address
312         this.broadcast = network | ~netmask;
313     }
314 
315     /**
316      * Constructs an instance from a dotted decimal address and a dotted decimal mask.
317      *
318      * @param address An IP address, e.g. "192.168.0.1"
319      * @param mask    A dotted decimal netmask e.g. "255.255.0.0"
320      * @throws IllegalArgumentException if the address or mask is invalid, i.e. does not match n.n.n.n where n=1-3 decimal digits and the mask is not all zeros
321      */
322     public SubnetUtils(final String address, final String mask) {
323         this.address = toInteger(address);
324         this.netmask = toInteger(mask);
325 
326         if ((this.netmask & -this.netmask) - 1 != ~this.netmask) {
327             throw new IllegalArgumentException(String.format(PARSE_FAIL, mask));
328         }
329 
330         // Calculate base network address
331         this.network = this.address & this.netmask;
332 
333         // Calculate broadcast address
334         this.broadcast = this.network | ~this.netmask;
335     }
336 
337     /**
338      * Gets a {@link SubnetInfo} instance that contains subnet-specific statistics
339      *
340      * @return new instance
341      */
342     public final SubnetInfo getInfo() {
343         return new SubnetInfo();
344     }
345 
346     public SubnetUtils getNext() {
347         return new SubnetUtils(getInfo().getNextAddress(), getInfo().getNetmask());
348     }
349 
350     public SubnetUtils getPrevious() {
351         return new SubnetUtils(getInfo().getPreviousAddress(), getInfo().getNetmask());
352     }
353 
354     /**
355      * Tests if the return value of {@link SubnetInfo#getAddressCount()} includes the network and broadcast addresses.
356      *
357      * @since 2.2
358      * @return true if the host count includes the network and broadcast addresses
359      */
360     public boolean isInclusiveHostCount() {
361         return inclusiveHostCount;
362     }
363 
364     /**
365      * Sets to <code>true</code> if you want the return value of {@link SubnetInfo#getAddressCount()} to include the network and broadcast addresses. This also
366      * applies to {@link SubnetInfo#isInRange(int)}
367      *
368      * @param inclusiveHostCount true if network and broadcast addresses are to be included
369      * @since 2.2
370      */
371     public void setInclusiveHostCount(final boolean inclusiveHostCount) {
372         this.inclusiveHostCount = inclusiveHostCount;
373     }
374 
375 }