1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20
21 package org.apache.mina.filter.firewall;
22
23 import java.net.Inet4Address;
24 import java.net.InetAddress;
25
26 /**
27 * A IP subnet using the CIDR notation. Currently, only IP version 4
28 * address are supported.
29 *
30 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
31 */
32 public class Subnet {
33
34 private static final int IP_MASK = 0x80000000;
35
36 private static final int BYTE_MASK = 0xFF;
37
38 private InetAddress subnet;
39
40 private int subnetInt;
41
42 private int subnetMask;
43
44 private int suffix;
45
46 /**
47 * Creates a subnet from CIDR notation. For example, the subnet
48 * 192.168.0.0/24 would be created using the {@link InetAddress}
49 * 192.168.0.0 and the mask 24.
50 * @param subnet The {@link InetAddress} of the subnet
51 * @param mask The mask
52 */
53 public Subnet(InetAddress subnet, int mask) {
54 if (subnet == null) {
55 throw new IllegalArgumentException("Subnet address can not be null");
56 }
57 if (!(subnet instanceof Inet4Address)) {
58 throw new IllegalArgumentException("Only IPv4 supported");
59 }
60
61 if (mask < 0 || mask > 32) {
62 throw new IllegalArgumentException("Mask has to be an integer between 0 and 32");
63 }
64
65 this.subnet = subnet;
66 this.subnetInt = toInt(subnet);
67 this.suffix = mask;
68
69 // binary mask for this subnet
70 this.subnetMask = IP_MASK >> (mask - 1);
71 }
72
73 /**
74 * Converts an IP address into an integer
75 */
76 private int toInt(InetAddress inetAddress) {
77 byte[] address = inetAddress.getAddress();
78 int result = 0;
79 for (int i = 0; i < address.length; i++) {
80 result <<= 8;
81 result |= address[i] & BYTE_MASK;
82 }
83 return result;
84 }
85
86 /**
87 * Converts an IP address to a subnet using the provided
88 * mask
89 * @param address The address to convert into a subnet
90 * @return The subnet as an integer
91 */
92 private int toSubnet(InetAddress address) {
93 return toInt(address) & subnetMask;
94 }
95
96 /**
97 * Checks if the {@link InetAddress} is within this subnet
98 * @param address The {@link InetAddress} to check
99 * @return True if the address is within this subnet, false otherwise
100 */
101 public boolean inSubnet(InetAddress address) {
102 return toSubnet(address) == subnetInt;
103 }
104
105 /**
106 * @see Object#toString()
107 */
108 @Override
109 public String toString() {
110 return subnet.getHostAddress() + "/" + suffix;
111 }
112
113 @Override
114 public boolean equals(Object obj) {
115 if (!(obj instanceof Subnet)) {
116 return false;
117 }
118
119 Subnet other = (Subnet) obj;
120
121 return other.subnetInt == subnetInt && other.suffix == suffix;
122 }
123
124 }