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package org.apache.tomcat.util.net;

IPv6 utilities.

For the moment, it only contains function to canonicalize IPv6 address into RFC 5952 form.

/** * <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;

Convert IPv6 address into RFC 5952 form. E.g. 2001:db8:0:1:0:0:0:1 -> 2001:db8:0:1::1

Method is null safe, and if IPv4 address or host name is passed to the method it is returned without any processing.

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).

The behaviour of this method is undefined if an invalid IPv6 address is passed in as input.

Params:
  • ipv6Address – String representing valid IPv6 address.
Throws:
Returns:String representing IPv6 in canonical form.
/** * <p>Convert IPv6 address into RFC 5952 form. * E.g. 2001:db8:0:1:0:0:0:1 -&gt; 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 -&gt; * ::ffff:192.0.2.1), and zone ID (e.g. fe80:0:0:0:f0f0:c0c0:1919:1234%4 * -&gt; 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.
Params:
  • input – Any string or null
Returns:true, if input string contains only hex digits and at least two colons, before '.' or '%' character
/** * 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; } }