SubnetUtils.java
/*
* 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;
/**
* Performs some subnet calculations given a network address and a subnet mask.
*
* @see "http://www.faqs.org/rfcs/rfc1519.html"
* @since 2.0
*/
public class SubnetUtils {
/**
* Convenience container for subnet summary information.
*/
public final class SubnetInfo {
/** Mask to convert unsigned int to a long (i.e. keep 32 bits). */
private static final long UNSIGNED_INT_MASK = 0x0FFFFFFFFL;
private SubnetInfo() {
}
public int asInteger(final String address) {
return toInteger(address);
}
private long broadcastLong() {
return broadcast & UNSIGNED_INT_MASK;
}
/**
* Converts a 4-element array into dotted decimal format.
*/
private String format(final int[] octets) {
final int last = octets.length - 1;
final StringBuilder builder = new StringBuilder();
for (int i = 0;; i++) {
builder.append(octets[i]);
if (i == last) {
return builder.toString();
}
builder.append('.');
}
}
public String getAddress() {
return format(toArray(address));
}
/**
* Gets the count of available addresses. Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
*
* @return the count of addresses, may be zero.
* @throws RuntimeException if the correct count is greater than {@code Integer.MAX_VALUE}
* @deprecated (3.4) use {@link #getAddressCountLong()} instead
*/
@Deprecated
public int getAddressCount() {
final long countLong = getAddressCountLong();
if (countLong > Integer.MAX_VALUE) {
throw new IllegalStateException("Count is larger than an integer: " + countLong);
}
// Cannot be negative here
return (int) countLong;
}
/**
* Gets the count of available addresses. Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
*
* @return the count of addresses, may be zero.
* @since 3.4
*/
public long getAddressCountLong() {
final long b = broadcastLong();
final long n = networkLong();
final long count = b - n + (isInclusiveHostCount() ? 1 : -1);
return count < 0 ? 0 : count;
}
public String[] getAllAddresses() {
final int ct = getAddressCount();
final String[] addresses = new String[ct];
if (ct == 0) {
return addresses;
}
for (int add = low(), j = 0; add <= high(); ++add, ++j) {
addresses[j] = format(toArray(add));
}
return addresses;
}
public String getBroadcastAddress() {
return format(toArray(broadcast));
}
public String getCidrSignature() {
return format(toArray(address)) + "/" + Integer.bitCount(netmask);
}
/**
* Gets the high address as a dotted IP address. Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
*
* @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
*/
public String getHighAddress() {
return format(toArray(high()));
}
/**
* Gets the low address as a dotted IP address. Will be zero for CIDR/31 and CIDR/32 if the inclusive flag is false.
*
* @return the IP address in dotted format, may be "0.0.0.0" if there is no valid address
*/
public String getLowAddress() {
return format(toArray(low()));
}
public String getNetmask() {
return format(toArray(netmask));
}
public String getNetworkAddress() {
return format(toArray(network));
}
public String getNextAddress() {
return format(toArray(address + 1));
}
public String getPreviousAddress() {
return format(toArray(address - 1));
}
private int high() {
return isInclusiveHostCount() ? broadcast : broadcastLong() - networkLong() > 1 ? broadcast - 1 : 0;
}
/**
* Tests if the parameter <code>address</code> is in the range of usable endpoint addresses for this subnet. This excludes the network and broadcast
* addresses by default. Use {@link SubnetUtils#setInclusiveHostCount(boolean)} to change this.
*
* @param address the address to check
* @return true if it is in range
* @since 3.4 (made public)
*/
public boolean isInRange(final int address) {
if (address == 0) { // cannot ever be in range; rejecting now avoids problems with CIDR/31,32
return false;
}
final long addLong = address & UNSIGNED_INT_MASK;
final long lowLong = low() & UNSIGNED_INT_MASK;
final long highLong = high() & UNSIGNED_INT_MASK;
return addLong >= lowLong && addLong <= highLong;
}
/**
* Tests if the parameter <code>address</code> is in the range of usable endpoint addresses for this subnet. This excludes the network and broadcast
* addresses. Use {@link SubnetUtils#setInclusiveHostCount(boolean)} to change this.
*
* @param address A dot-delimited IPv4 address, e.g. "192.168.0.1"
* @return True if in range, false otherwise
*/
public boolean isInRange(final String address) {
return isInRange(toInteger(address));
}
private int low() {
return isInclusiveHostCount() ? network : broadcastLong() - networkLong() > 1 ? network + 1 : 0;
}
/** long versions of the values (as unsigned int) which are more suitable for range checking. */
private long networkLong() {
return network & UNSIGNED_INT_MASK;
}
/**
* Converts a packed integer address into a 4-element array
*/
private int[] toArray(final int val) {
final int[] ret = new int[4];
for (int j = 3; j >= 0; --j) {
ret[j] |= val >>> 8 * (3 - j) & 0xff;
}
return ret;
}
/**
* {@inheritDoc}
*
* @since 2.2
*/
@Override
public String toString() {
final StringBuilder buf = new StringBuilder();
// @formatter:off
buf.append("CIDR Signature:\t[").append(getCidrSignature()).append("]\n")
.append(" Netmask: [").append(getNetmask()).append("]\n")
.append(" Network: [").append(getNetworkAddress()).append("]\n")
.append(" Broadcast: [").append(getBroadcastAddress()).append("]\n")
.append(" First address: [").append(getLowAddress()).append("]\n")
.append(" Last address: [").append(getHighAddress()).append("]\n")
.append(" Address Count: [").append(getAddressCountLong()).append("]\n");
// @formatter:on
return buf.toString();
}
}
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{1,2})"; // 0 -> 32
private static final Pattern ADDRESS_PATTERN = Pattern.compile(IP_ADDRESS);
private static final Pattern CIDR_PATTERN = Pattern.compile(SLASH_FORMAT);
private static final int NBITS = 32;
private static final String PARSE_FAIL = "Could not parse [%s]";
/*
* Extracts the components of a dotted decimal address and pack into an integer using a regex match
*/
private static int matchAddress(final Matcher matcher) {
int addr = 0;
for (int i = 1; i <= 4; ++i) {
final int n = rangeCheck(Integer.parseInt(matcher.group(i)), 0, 255);
addr |= (n & 0xff) << 8 * (4 - i);
}
return addr;
}
/*
* 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.
*/
private static int rangeCheck(final int value, final int begin, final int end) {
if (value >= begin && value <= end) { // (begin,end]
return value;
}
throw new IllegalArgumentException("Value [" + value + "] not in range [" + begin + "," + end + "]");
}
/*
* Converts a dotted decimal format address to a packed integer format
*/
private static int toInteger(final String address) {
final Matcher matcher = ADDRESS_PATTERN.matcher(address);
if (matcher.matches()) {
return matchAddress(matcher);
}
throw new IllegalArgumentException(String.format(PARSE_FAIL, address));
}
private final int netmask;
private final int address;
private final int network;
private final int broadcast;
/** Whether the broadcast/network address are included in host count */
private boolean inclusiveHostCount;
/**
* Constructs an instance from a CIDR-notation string, e.g. "192.168.0.1/16"
*
* @param cidrNotation A CIDR-notation string, e.g. "192.168.0.1/16"
* @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
* 0-32
*/
public SubnetUtils(final String cidrNotation) {
final Matcher matcher = CIDR_PATTERN.matcher(cidrNotation);
if (!matcher.matches()) {
throw new IllegalArgumentException(String.format(PARSE_FAIL, cidrNotation));
}
this.address = matchAddress(matcher);
// Create a binary netmask from the number of bits specification /x
final int trailingZeroes = NBITS - rangeCheck(Integer.parseInt(matcher.group(5)), 0, NBITS);
//
// An IPv4 netmask consists of 32 bits, a contiguous sequence
// of the specified number of ones followed by all zeros.
// So, it can be obtained by shifting an unsigned integer (32 bits) to the left by
// the number of trailing zeros which is (32 - the # bits specification).
// Note that there is no unsigned left shift operator, so we have to use
// a long to ensure that the left-most bit is shifted out correctly.
//
this.netmask = (int) (0x0FFFFFFFFL << trailingZeroes);
// Calculate base network address
this.network = address & netmask;
// Calculate broadcast address
this.broadcast = network | ~netmask;
}
/**
* Constructs an instance from a dotted decimal address and a dotted decimal mask.
*
* @param address An IP address, e.g. "192.168.0.1"
* @param mask A dotted decimal netmask e.g. "255.255.0.0"
* @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
*/
public SubnetUtils(final String address, final String mask) {
this.address = toInteger(address);
this.netmask = toInteger(mask);
if ((this.netmask & -this.netmask) - 1 != ~this.netmask) {
throw new IllegalArgumentException(String.format(PARSE_FAIL, mask));
}
// Calculate base network address
this.network = this.address & this.netmask;
// Calculate broadcast address
this.broadcast = this.network | ~this.netmask;
}
/**
* Gets a {@link SubnetInfo} instance that contains subnet-specific statistics
*
* @return new instance
*/
public final SubnetInfo getInfo() {
return new SubnetInfo();
}
public SubnetUtils getNext() {
return new SubnetUtils(getInfo().getNextAddress(), getInfo().getNetmask());
}
public SubnetUtils getPrevious() {
return new SubnetUtils(getInfo().getPreviousAddress(), getInfo().getNetmask());
}
/**
* Tests if the return value of {@link SubnetInfo#getAddressCount()} includes the network and broadcast addresses.
*
* @since 2.2
* @return true if the host count includes the network and broadcast addresses
*/
public boolean isInclusiveHostCount() {
return inclusiveHostCount;
}
/**
* Sets to {@code true} if you want the return value of {@link SubnetInfo#getAddressCount()} to include the network and broadcast addresses. This also
* applies to {@link SubnetInfo#isInRange(int)}
*
* @param inclusiveHostCount true if network and broadcast addresses are to be included
* @since 2.2
*/
public void setInclusiveHostCount(final boolean inclusiveHostCount) {
this.inclusiveHostCount = inclusiveHostCount;
}
}