IPv6Utils.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.tomcat.util.net;
/**
* <p>IPv6 utilities.
* <p>For the moment, it only contains function to canonicalize IPv6 address
* into RFC 5952 form.
*/
public class IPv6Utils {
private static final int MAX_NUMBER_OF_GROUPS = 8;
private static final int MAX_GROUP_LENGTH = 4;
/**
* <p>Convert IPv6 address into RFC 5952 form.
* E.g. 2001:db8:0:1:0:0:0:1 -> 2001:db8:0:1::1</p>
*
* <p>Method is null safe, and if IPv4 address or host name is passed to the
* method it is returned without any processing.</p>
*
* <p>Method also supports IPv4 in IPv6 (e.g. 0:0:0:0:0:ffff:192.0.2.1 ->
* ::ffff:192.0.2.1), and zone ID (e.g. fe80:0:0:0:f0f0:c0c0:1919:1234%4
* -> fe80::f0f0:c0c0:1919:1234%4).</p>
*
* <p>The behaviour of this method is undefined if an invalid IPv6 address
* is passed in as input.</p>
*
* @param ipv6Address String representing valid IPv6 address.
* @return String representing IPv6 in canonical form.
* @throws IllegalArgumentException if IPv6 format is unacceptable.
*/
public static String canonize(String ipv6Address) throws IllegalArgumentException {
if (ipv6Address == null) {
return null;
}
// Definitely not an IPv6, return untouched input.
if (!mayBeIPv6Address(ipv6Address)) {
return ipv6Address;
}
// Length without zone ID (%zone) or IPv4 address
int ipv6AddressLength = ipv6Address.length();
if (ipv6Address.contains(".")) {
// IPv4 in IPv6
// e.g. 0:0:0:0:0:FFFF:127.0.0.1
int lastColonPos = ipv6Address.lastIndexOf(':');
int lastColonsPos = ipv6Address.lastIndexOf("::");
if (lastColonsPos >= 0 && lastColonPos == lastColonsPos + 1) {
/*
* IPv6 part ends with two consecutive colons,
* last colon is part of IPv6 format.
* e.g. ::127.0.0.1
*/
ipv6AddressLength = lastColonPos + 1;
} else {
/*
* IPv6 part ends with only one colon,
* last colon is not part of IPv6 format.
* e.g. ::FFFF:127.0.0.1
*/
ipv6AddressLength = lastColonPos;
}
} else if (ipv6Address.contains("%")) {
// Zone ID
// e.g. fe80:0:0:0:f0f0:c0c0:1919:1234%4
ipv6AddressLength = ipv6Address.lastIndexOf('%');
}
StringBuilder result = new StringBuilder();
char [][] groups = new char[MAX_NUMBER_OF_GROUPS][MAX_GROUP_LENGTH];
int groupCounter = 0;
int charInGroupCounter = 0;
// Index of the current zeroGroup, -1 means not found.
int zeroGroupIndex = -1;
int zeroGroupLength = 0;
// maximum length zero group, if there is more then one, then first one
int maxZeroGroupIndex = -1;
int maxZeroGroupLength = 0;
boolean isZero = true;
boolean groupStart = true;
/*
* Two consecutive colons, initial expansion.
* e.g. 2001:db8:0:0:1::1 -> 2001:db8:0:0:1:0:0:1
*/
StringBuilder expanded = new StringBuilder(ipv6Address);
int colonsPos = ipv6Address.indexOf("::");
int length = ipv6AddressLength;
int change = 0;
if (colonsPos >= 0 && colonsPos < ipv6AddressLength - 1) {
int colonCounter = 0;
for (int i = 0; i < ipv6AddressLength; i++) {
if (ipv6Address.charAt(i) == ':') {
colonCounter++;
}
}
if (colonsPos == 0) {
expanded.insert(0, "0");
change = change + 1;
}
for (int i = 0; i < MAX_NUMBER_OF_GROUPS - colonCounter; i++) {
expanded.insert(colonsPos + 1, "0:");
change = change + 2;
}
if (colonsPos == ipv6AddressLength - 2) {
expanded.setCharAt(colonsPos + change + 1, '0');
} else {
expanded.deleteCharAt(colonsPos + change + 1);
change = change - 1;
}
length = length + change;
}
// Processing one char at the time
for (int charCounter = 0; charCounter < length; charCounter++) {
char c = expanded.charAt(charCounter);
if (c >= 'A' && c <= 'F') {
c = (char) (c + 32);
}
if (c != ':') {
groups[groupCounter][charInGroupCounter] = c;
if (!(groupStart && c == '0')) {
++charInGroupCounter;
groupStart = false;
}
if (c != '0') {
isZero = false;
}
}
if (c == ':' || charCounter == (length - 1)) {
// We reached end of current group
if (isZero) {
++zeroGroupLength;
if (zeroGroupIndex == -1) {
zeroGroupIndex = groupCounter;
}
}
if (!isZero || charCounter == (length - 1)) {
// We reached end of zero group
if (zeroGroupLength > maxZeroGroupLength) {
maxZeroGroupLength = zeroGroupLength;
maxZeroGroupIndex = zeroGroupIndex;
}
zeroGroupLength = 0;
zeroGroupIndex = -1;
}
++groupCounter;
charInGroupCounter = 0;
isZero = true;
groupStart = true;
}
}
int numberOfGroups = groupCounter;
// Output results
for (groupCounter = 0; groupCounter < numberOfGroups; groupCounter++) {
if (maxZeroGroupLength <= 1 || groupCounter < maxZeroGroupIndex
|| groupCounter >= maxZeroGroupIndex + maxZeroGroupLength) {
for (int j = 0; j < MAX_GROUP_LENGTH; j++) {
if (groups[groupCounter][j] != 0) {
result.append(groups[groupCounter][j]);
}
}
if (groupCounter < (numberOfGroups - 1)
&& (groupCounter != maxZeroGroupIndex - 1
|| maxZeroGroupLength <= 1)) {
result.append(':');
}
} else if (groupCounter == maxZeroGroupIndex) {
result.append("::");
}
}
// Solve problem with three colons in IPv4 in IPv6 format
// e.g. 0:0:0:0:0:0:127.0.0.1 -> :::127.0.0.1 -> ::127.0.0.1
int resultLength = result.length();
if (result.charAt(resultLength - 1) == ':' && ipv6AddressLength < ipv6Address.length()
&& ipv6Address.charAt(ipv6AddressLength) == ':') {
result.delete(resultLength - 1, resultLength);
}
/*
* Append IPv4 from IPv4-in-IPv6 format or Zone ID
*/
for (int i = ipv6AddressLength; i < ipv6Address.length(); i++) {
result.append(ipv6Address.charAt(i));
}
return result.toString();
}
/**
* Heuristic check if string might be an IPv6 address.
*
* @param input Any string or null
* @return true, if input string contains only hex digits and at least two colons, before '.' or '%' character
*/
static boolean mayBeIPv6Address(String input) {
if (input == null) {
return false;
}
int colonsCounter = 0;
int length = input.length();
for (int i = 0; i < length; i++) {
char c = input.charAt(i);
if (c == '.' || c == '%') {
// IPv4 in IPv6 or Zone ID detected, end of checking.
break;
}
if (!((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f')
|| (c >= 'A' && c <= 'F') || c == ':')) {
return false;
} else if (c == ':') {
colonsCounter++;
}
}
if (colonsCounter < 2) {
return false;
}
return true;
}
}