InetAddresses.java
/*
* Copyright (C) 2008 The Guava Authors
*
* Licensed 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.glassfish.jersey.internal.guava;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
/**
* Static utility methods pertaining to {@link InetAddress} instances.
* <p>
* <p><b>Important note:</b> Unlike {@code InetAddress.getByName()}, the
* methods of this class never cause DNS services to be accessed. For
* this reason, you should prefer these methods as much as possible over
* their JDK equivalents whenever you are expecting to handle only
* IP address string literals -- there is no blocking DNS penalty for a
* malformed string.
* <p>
* <p>When dealing with {@link Inet4Address} and {@link Inet6Address}
* objects as byte arrays (vis. {@code InetAddress.getAddress()}) they
* are 4 and 16 bytes in length, respectively, and represent the address
* in network byte order.
* <p>
* <p>Examples of IP addresses and their byte representations:
* <ul>
* <li>The IPv4 loopback address, {@code "127.0.0.1"}.<br/>
* {@code 7f 00 00 01}
* <p>
* <li>The IPv6 loopback address, {@code "::1"}.<br/>
* {@code 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01}
* <p>
* <li>From the IPv6 reserved documentation prefix ({@code 2001:db8::/32}),
* {@code "2001:db8::1"}.<br/>
* {@code 20 01 0d b8 00 00 00 00 00 00 00 00 00 00 00 01}
* <p>
* <li>An IPv6 "IPv4 compatible" (or "compat") address,
* {@code "::192.168.0.1"}.<br/>
* {@code 00 00 00 00 00 00 00 00 00 00 00 00 c0 a8 00 01}
* <p>
* <li>An IPv6 "IPv4 mapped" address, {@code "::ffff:192.168.0.1"}.<br/>
* {@code 00 00 00 00 00 00 00 00 00 00 ff ff c0 a8 00 01}
* </ul>
* <p>
* <p>A few notes about IPv6 "IPv4 mapped" addresses and their observed
* use in Java.
* <br><br>
* "IPv4 mapped" addresses were originally a representation of IPv4
* addresses for use on an IPv6 socket that could receive both IPv4
* and IPv6 connections (by disabling the {@code IPV6_V6ONLY} socket
* option on an IPv6 socket). Yes, it's confusing. Nevertheless,
* these "mapped" addresses were never supposed to be seen on the
* wire. That assumption was dropped, some say mistakenly, in later
* RFCs with the apparent aim of making IPv4-to-IPv6 transition simpler.
* <p>
* <p>Technically one <i>can</i> create a 128bit IPv6 address with the wire
* format of a "mapped" address, as shown above, and transmit it in an
* IPv6 packet header. However, Java's InetAddress creation methods
* appear to adhere doggedly to the original intent of the "mapped"
* address: all "mapped" addresses return {@link Inet4Address} objects.
* <p>
* <p>For added safety, it is common for IPv6 network operators to filter
* all packets where either the source or destination address appears to
* be a "compat" or "mapped" address. Filtering suggestions usually
* recommend discarding any packets with source or destination addresses
* in the invalid range {@code ::/3}, which includes both of these bizarre
* address formats. For more information on "bogons", including lists
* of IPv6 bogon space, see:
* <p>
* <ul>
* <li><a target="_parent"
* href="http://en.wikipedia.org/wiki/Bogon_filtering"
* >http://en.wikipedia.org/wiki/Bogon_filtering</a>
* <li><a target="_parent"
* href="http://www.cymru.com/Bogons/ipv6.txt"
* >http://www.cymru.com/Bogons/ipv6.txt</a>
* <li><a target="_parent"
* href="http://www.cymru.com/Bogons/v6bogon.html"
* >http://www.cymru.com/Bogons/v6bogon.html</a>
* <li><a target="_parent"
* href="http://www.space.net/~gert/RIPE/ipv6-filters.html"
* >http://www.space.net/~gert/RIPE/ipv6-filters.html</a>
* </ul>
*
* @author Erik Kline
* @since 5.0
*/
public final class InetAddresses {
private static final int IPV4_PART_COUNT = 4;
private static final int IPV6_PART_COUNT = 8;
private InetAddresses() {
}
private static byte[] ipStringToBytes(String ipString) {
// Make a first pass to categorize the characters in this string.
boolean hasColon = false;
boolean hasDot = false;
for (int i = 0; i < ipString.length(); i++) {
char c = ipString.charAt(i);
if (c == '.') {
hasDot = true;
} else if (c == ':') {
if (hasDot) {
return null; // Colons must not appear after dots.
}
hasColon = true;
} else if (Character.digit(c, 16) == -1) {
return null; // Everything else must be a decimal or hex digit.
}
}
// Now decide which address family to parse.
if (hasColon) {
if (hasDot) {
ipString = convertDottedQuadToHex(ipString);
if (ipString == null) {
return null;
}
}
return textToNumericFormatV6(ipString);
} else if (hasDot) {
return textToNumericFormatV4(ipString);
}
return null;
}
private static byte[] textToNumericFormatV4(String ipString) {
String[] address = ipString.split("\\.", IPV4_PART_COUNT + 1);
if (address.length != IPV4_PART_COUNT) {
return null;
}
byte[] bytes = new byte[IPV4_PART_COUNT];
try {
for (int i = 0; i < bytes.length; i++) {
bytes[i] = parseOctet(address[i]);
}
} catch (NumberFormatException ex) {
return null;
}
return bytes;
}
private static byte[] textToNumericFormatV6(String ipString) {
// An address can have [2..8] colons, and N colons make N+1 parts.
String[] parts = ipString.split(":", IPV6_PART_COUNT + 2);
if (parts.length < 3 || parts.length > IPV6_PART_COUNT + 1) {
return null;
}
// Disregarding the endpoints, find "::" with nothing in between.
// This indicates that a run of zeroes has been skipped.
int skipIndex = -1;
for (int i = 1; i < parts.length - 1; i++) {
if (parts[i].length() == 0) {
if (skipIndex >= 0) {
return null; // Can't have more than one ::
}
skipIndex = i;
}
}
int partsHi; // Number of parts to copy from above/before the "::"
int partsLo; // Number of parts to copy from below/after the "::"
if (skipIndex >= 0) {
// If we found a "::", then check if it also covers the endpoints.
partsHi = skipIndex;
partsLo = parts.length - skipIndex - 1;
if (parts[0].length() == 0 && --partsHi != 0) {
return null; // ^: requires ^::
}
if (parts[parts.length - 1].length() == 0 && --partsLo != 0) {
return null; // :$ requires ::$
}
} else {
// Otherwise, allocate the entire address to partsHi. The endpoints
// could still be empty, but parseHextet() will check for that.
partsHi = parts.length;
partsLo = 0;
}
// If we found a ::, then we must have skipped at least one part.
// Otherwise, we must have exactly the right number of parts.
int partsSkipped = IPV6_PART_COUNT - (partsHi + partsLo);
if (!(skipIndex >= 0 ? partsSkipped >= 1 : partsSkipped == 0)) {
return null;
}
// Now parse the hextets into a byte array.
ByteBuffer rawBytes = ByteBuffer.allocate(2 * IPV6_PART_COUNT);
try {
for (int i = 0; i < partsHi; i++) {
rawBytes.putShort(parseHextet(parts[i]));
}
for (int i = 0; i < partsSkipped; i++) {
rawBytes.putShort((short) 0);
}
for (int i = partsLo; i > 0; i--) {
rawBytes.putShort(parseHextet(parts[parts.length - i]));
}
} catch (NumberFormatException ex) {
return null;
}
return rawBytes.array();
}
private static String convertDottedQuadToHex(String ipString) {
int lastColon = ipString.lastIndexOf(':');
String initialPart = ipString.substring(0, lastColon + 1);
String dottedQuad = ipString.substring(lastColon + 1);
byte[] quad = textToNumericFormatV4(dottedQuad);
if (quad == null) {
return null;
}
String penultimate = Integer.toHexString(((quad[0] & 0xff) << 8) | (quad[1] & 0xff));
String ultimate = Integer.toHexString(((quad[2] & 0xff) << 8) | (quad[3] & 0xff));
return initialPart + penultimate + ":" + ultimate;
}
private static byte parseOctet(String ipPart) {
// Note: we already verified that this string contains only hex digits.
int octet = Integer.parseInt(ipPart);
// Disallow leading zeroes, because no clear standard exists on
// whether these should be interpreted as decimal or octal.
if (octet > 255 || (ipPart.startsWith("0") && ipPart.length() > 1)) {
throw new NumberFormatException();
}
return (byte) octet;
}
private static short parseHextet(String ipPart) {
// Note: we already verified that this string contains only hex digits.
int hextet = Integer.parseInt(ipPart, 16);
if (hextet > 0xffff) {
throw new NumberFormatException();
}
return (short) hextet;
}
/**
* Convert a byte array into an InetAddress.
* <p>
* {@link InetAddress#getByAddress} is documented as throwing a checked
* exception "if IP address if of illegal length." We replace it with
* an unchecked exception, for use by callers who already know that addr
* is an array of length 4 or 16.
*
* @param addr the raw 4-byte or 16-byte IP address in big-endian order
* @return an InetAddress object created from the raw IP address
*/
private static InetAddress bytesToInetAddress(byte[] addr) {
try {
return InetAddress.getByAddress(addr);
} catch (UnknownHostException e) {
throw new AssertionError(e);
}
}
/**
* Returns an InetAddress representing the literal IPv4 or IPv6 host
* portion of a URL, encoded in the format specified by RFC 3986 section 3.2.2.
* <p>
* <p>This function is similar to {@link InetAddresses#forString(String)},
* however, it requires that IPv6 addresses are surrounded by square brackets.
*
* @param hostAddr A RFC 3986 section 3.2.2 encoded IPv4 or IPv6 address
* @return an InetAddress representing the address in {@code hostAddr};
* otherwise null if {@code hostAddr} is not a valid IPv4 address,
* or IPv6 address surrounded * by square brackets
*/
private static InetAddress forUriStringNoThrow(String hostAddr) {
Preconditions.checkNotNull(hostAddr);
// Decide if this should be an IPv6 or IPv4 address.
String ipString;
int expectBytes;
if (hostAddr.startsWith("[") && hostAddr.endsWith("]")) {
ipString = hostAddr.substring(1, hostAddr.length() - 1);
expectBytes = 16;
} else {
ipString = hostAddr;
expectBytes = 4;
}
// Parse the address, and make sure the length/version is correct.
byte[] addr = ipStringToBytes(ipString);
if (addr == null || addr.length != expectBytes) {
return null;
}
return bytesToInetAddress(addr);
}
/**
* Returns {@code true} if the supplied string is a valid URI IP string
* literal, {@code false} otherwise.
*
* @param ipString {@code String} to evaluated as an IP URI host string literal
* @return {@code true} if the argument is a valid IP URI host
*/
public static boolean isUriInetAddress(String ipString) {
return forUriStringNoThrow(ipString) != null;
}
/**
* Evaluates whether the argument is an "IPv4 mapped" IPv6 address.
* <p>
* <p>An "IPv4 mapped" address is anything in the range ::ffff:0:0/96
* (sometimes written as ::ffff:0.0.0.0/96), with the last 32 bits
* interpreted as an IPv4 address.
* <p>
* <p>For more on IPv4 mapped addresses see section 2.5.5.2 of
* <a target="_parent"
* href="http://tools.ietf.org/html/rfc4291#section-2.5.5.2"
* >http://tools.ietf.org/html/rfc4291</a>
* <p>
* <p>Note: This method takes a {@code String} argument because
* {@link InetAddress} automatically collapses mapped addresses to IPv4.
* (It is actually possible to avoid this using one of the obscure
* {@link Inet6Address} methods, but it would be unwise to depend on such
* a poorly-documented feature.)
*
* @param ipString {@code String} to be examined for embedded IPv4-mapped IPv6 address format
* @return {@code true} if the argument is a valid "mapped" address
* @since 10.0
*/
public static boolean isMappedIPv4Address(String ipString) {
byte[] bytes = ipStringToBytes(ipString);
if (bytes != null && bytes.length == 16) {
for (int i = 0; i < 10; i++) {
if (bytes[i] != 0) {
return false;
}
}
for (int i = 10; i < 12; i++) {
if (bytes[i] != (byte) 0xff) {
return false;
}
}
return true;
}
return false;
}
}