/*
* 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.araqne.logdb.impl;
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>
* <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>
* 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>
* 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}
*
* <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}
*
* <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}
*
* <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}
*
* <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>
* 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>
* 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>
* 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:
*
* <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() {
}
/**
* Returns the {@link InetAddress} having the given string representation.
*
* <p>
* This deliberately avoids all nameservice lookups (e.g. no DNS).
*
* @param ipString
* {@code String} containing an IPv4 or IPv6 string literal, e.g.
* {@code "192.168.0.1"} or {@code "2001:db8::1"}
* @return {@link InetAddress} representing the argument
* @throws IllegalArgumentException
* if the argument is not a valid IP string literal
*/
public static InetAddress forString(String ipString) {
byte[] addr = ipStringToBytes(ipString);
// The argument was malformed, i.e. not an IP string literal.
if (addr == null)
return null;
return bytesToInetAddress(addr);
}
/**
* Returns {@code true} if the supplied string is a valid IP string literal,
* {@code false} otherwise.
*
* @param ipString
* {@code String} to evaluated as an IP string literal
* @return {@code true} if the argument is a valid IP string literal
*/
public static boolean isInetAddress(String ipString) {
return ipStringToBytes(ipString) != null;
}
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.
*
* {@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);
}
}
/**
* Evaluates whether the argument is an IPv6 "compat" address.
*
* <p>
* An "IPv4 compatible", or "compat", address is one with 96 leading bits of
* zero, with the remaining 32 bits interpreted as an IPv4 address. These
* are conventionally represented in string literals as
* {@code "::192.168.0.1"}, though {@code "::c0a8:1"} is also considered an
* IPv4 compatible address (and equivalent to {@code "::192.168.0.1"}).
*
* <p>
* For more on IPv4 compatible addresses see section 2.5.5.1 of <a
* target="_parent"
* href="http://tools.ietf.org/html/rfc4291#section-2.5.5.1"
* >http://tools.ietf.org/html/rfc4291</a>
*
* <p>
* NOTE: This method is different from
* {@link Inet6Address#isIPv4CompatibleAddress} in that it more correctly
* classifies {@code "::"} and {@code "::1"} as proper IPv6 addresses (which
* they are), NOT IPv4 compatible addresses (which they are generally NOT
* considered to be).
*
* @param ip
* {@link Inet6Address} to be examined for embedded IPv4
* compatible address format
* @return {@code true} if the argument is a valid "compat" address
*/
public static boolean isCompatIPv4Address(Inet6Address ip) {
if (!ip.isIPv4CompatibleAddress()) {
return false;
}
byte[] bytes = ip.getAddress();
if ((bytes[12] == 0) && (bytes[13] == 0) && (bytes[14] == 0) && ((bytes[15] == 0) || (bytes[15] == 1))) {
return false;
}
return true;
}
}