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 /** 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 }