/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.net.util; import java.util.regex.Matcher; import java.util.regex.Pattern; /** * A class that performs some subnet calculations given a network address and a subnet mask. * @see http://www.faqs.org/rfcs/rfc1519.html * @author * @since 2.0 */ public class SubnetUtils { private static final String IP_ADDRESS = "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})"; private static final String SLASH_FORMAT = IP_ADDRESS + "/(\\d{1,3})"; private static final Pattern addressPattern = Pattern.compile(IP_ADDRESS); private static final Pattern cidrPattern = Pattern.compile(SLASH_FORMAT); private static final int NBITS = 32; private int netmask = 0; private int address = 0; private int network = 0; private int broadcast = 0; /** * Constructor that takes a CIDR-notation string, e.g. "192.168.0.1/16" * @param cidrNotation A CIDR-notation string, e.g. "192.168.0.1/16" */ public SubnetUtils(String cidrNotation) { calculate(cidrNotation); } /** * Constructor that takes two dotted decimal addresses. * @param address An IP address, e.g. "192.168.0.1" * @param mask A dotted decimal netmask e.g. "255.255.0.0" */ public SubnetUtils(String address, String mask) { calculate(toCidrNotation(address, mask)); } /** * Convenience container for subnet summary information. * */ public final class SubnetInfo { private SubnetInfo() {} private int netmask() { return netmask; } private int network() { return network; } private int address() { return address; } private int broadcast() { return broadcast; } private int low() { return network() + 1; } private int high() { return broadcast() - 1; } public boolean isInRange(String address) { return isInRange(toInteger(address)); } private boolean isInRange(int address) { return ((address-low()) <= (high()-low())); } public String getBroadcastAddress() { return format(toArray(broadcast())); } public String getNetworkAddress() { return format(toArray(network())); } public String getNetmask() { return format(toArray(netmask())); } public String getAddress() { return format(toArray(address())); } public String getLowAddress() { return format(toArray(low())); } public String getHighAddress() { return format(toArray(high())); } public int getAddressCount() { return (broadcast() - low()); } public int asInteger(String address) { return toInteger(address); } public String getCidrSignature() { return toCidrNotation( format(toArray(address())), format(toArray(netmask())) ); } public String[] getAllAddresses() { String[] addresses = new String[getAddressCount()]; for (int add = low(), j=0; add <= high(); ++add, ++j) { addresses[j] = format(toArray(add)); } return addresses; } } /** * Return a {@link SubnetInfo} instance that contains subnet-specific statistics * @return */ public final SubnetInfo getInfo() { return new SubnetInfo(); } /* * Initialize the internal fields from the supplied CIDR mask */ private void calculate(String mask) { Matcher matcher = cidrPattern.matcher(mask); if (matcher.matches()) { address = matchAddress(matcher); /* Create a binary netmask from the number of bits specification /x */ int cidrPart = rangeCheck(Integer.parseInt(matcher.group(5)), 0, NBITS-1); for (int j = 0; j < cidrPart; ++j) { netmask |= (1 << 31-j); } /* Calculate base network address */ network = (address & netmask); /* Calculate broadcast address */ broadcast = network | ~(netmask); } else throw new IllegalArgumentException("Could not parse [" + mask + "]"); } /* * Convert a dotted decimal format address to a packed integer format */ private int toInteger(String address) { Matcher matcher = addressPattern.matcher(address); if (matcher.matches()) { return matchAddress(matcher); } else throw new IllegalArgumentException("Could not parse [" + address + "]"); } /* * Convenience method to extract the components of a dotted decimal address and * pack into an integer using a regex match */ private int matchAddress(Matcher matcher) { int addr = 0; for (int i = 1; i <= 4; ++i) { int n = (rangeCheck(Integer.parseInt(matcher.group(i)), 0, 255)); addr |= ((n & 0xff) << 8*(4-i)); } return addr; } /* * Convert a packed integer address into a 4-element array */ private int[] toArray(int val) { int ret[] = new int[4]; for (int j = 3; j >= 0; --j) ret[j] |= ((val >>> 8*(3-j)) & (0xff)); return ret; } /* * Convert a 4-element array into dotted decimal format */ private String format(int[] octets) { StringBuilder str = new StringBuilder(); for (int i =0; i < octets.length; ++i){ str.append(octets[i]); if (i != octets.length - 1) { str.append("."); } } return str.toString(); } /* * Convenience function to check integer boundaries */ private int rangeCheck(int value, int begin, int end) { if (value >= begin && value <= end) return value; throw new IllegalArgumentException("Value out of range: [" + value + "]"); } /* * Count the number of 1-bits in a 32-bit integer using a divide-and-conquer strategy * see Hacker's Delight section 5.1 */ int pop(int x) { x = x - ((x >>> 1) & 0x55555555); x = (x & 0x33333333) + ((x >>> 2) & 0x33333333); x = (x + (x >>> 4)) & 0x0F0F0F0F; x = x + (x >>> 8); x = x + (x >>> 16); return x & 0x0000003F; } /* Convert two dotted decimal addresses to a single xxx.xxx.xxx.xxx/yy format * by counting the 1-bit population in the mask address. (It may be better to count * NBITS-#trailing zeroes for this case) */ private String toCidrNotation(String addr, String mask) { return addr + "/" + pop(toInteger(mask)); } }