| // Copyright (c) 2003-2004 Brian Wellington (bwelling@xbill.org) |
| |
| package org.xbill.DNS; |
| |
| import java.net.*; |
| |
| /** |
| * A set functions designed to deal with DNS names used in reverse mappings. |
| * For the IPv4 address a.b.c.d, the reverse map name is d.c.b.a.in-addr.arpa. |
| * For an IPv6 address, the reverse map name is ...ip6.arpa. |
| * |
| * @author Brian Wellington |
| */ |
| |
| public final class ReverseMap { |
| |
| private static Name inaddr4 = Name.fromConstantString("in-addr.arpa."); |
| private static Name inaddr6 = Name.fromConstantString("ip6.arpa."); |
| |
| /* Otherwise the class could be instantiated */ |
| private |
| ReverseMap() {} |
| |
| /** |
| * Creates a reverse map name corresponding to an address contained in |
| * an array of 4 bytes (for an IPv4 address) or 16 bytes (for an IPv6 address). |
| * @param addr The address from which to build a name. |
| * @return The name corresponding to the address in the reverse map. |
| */ |
| public static Name |
| fromAddress(byte [] addr) { |
| if (addr.length != 4 && addr.length != 16) |
| throw new IllegalArgumentException("array must contain " + |
| "4 or 16 elements"); |
| |
| StringBuffer sb = new StringBuffer(); |
| if (addr.length == 4) { |
| for (int i = addr.length - 1; i >= 0; i--) { |
| sb.append(addr[i] & 0xFF); |
| if (i > 0) |
| sb.append("."); |
| } |
| } else { |
| int [] nibbles = new int[2]; |
| for (int i = addr.length - 1; i >= 0; i--) { |
| nibbles[0] = (addr[i] & 0xFF) >> 4; |
| nibbles[1] = (addr[i] & 0xFF) & 0xF; |
| for (int j = nibbles.length - 1; j >= 0; j--) { |
| sb.append(Integer.toHexString(nibbles[j])); |
| if (i > 0 || j > 0) |
| sb.append("."); |
| } |
| } |
| } |
| |
| try { |
| if (addr.length == 4) |
| return Name.fromString(sb.toString(), inaddr4); |
| else |
| return Name.fromString(sb.toString(), inaddr6); |
| } |
| catch (TextParseException e) { |
| throw new IllegalStateException("name cannot be invalid"); |
| } |
| } |
| |
| /** |
| * Creates a reverse map name corresponding to an address contained in |
| * an array of 4 integers between 0 and 255 (for an IPv4 address) or 16 |
| * integers between 0 and 255 (for an IPv6 address). |
| * @param addr The address from which to build a name. |
| * @return The name corresponding to the address in the reverse map. |
| */ |
| public static Name |
| fromAddress(int [] addr) { |
| byte [] bytes = new byte[addr.length]; |
| for (int i = 0; i < addr.length; i++) { |
| if (addr[i] < 0 || addr[i] > 0xFF) |
| throw new IllegalArgumentException("array must " + |
| "contain values " + |
| "between 0 and 255"); |
| bytes[i] = (byte) addr[i]; |
| } |
| return fromAddress(bytes); |
| } |
| |
| /** |
| * Creates a reverse map name corresponding to an address contained in |
| * an InetAddress. |
| * @param addr The address from which to build a name. |
| * @return The name corresponding to the address in the reverse map. |
| */ |
| public static Name |
| fromAddress(InetAddress addr) { |
| return fromAddress(addr.getAddress()); |
| } |
| |
| /** |
| * Creates a reverse map name corresponding to an address contained in |
| * a String. |
| * @param addr The address from which to build a name. |
| * @return The name corresponding to the address in the reverse map. |
| * @throws UnknownHostException The string does not contain a valid address. |
| */ |
| public static Name |
| fromAddress(String addr, int family) throws UnknownHostException { |
| byte [] array = Address.toByteArray(addr, family); |
| if (array == null) |
| throw new UnknownHostException("Invalid IP address"); |
| return fromAddress(array); |
| } |
| |
| /** |
| * Creates a reverse map name corresponding to an address contained in |
| * a String. |
| * @param addr The address from which to build a name. |
| * @return The name corresponding to the address in the reverse map. |
| * @throws UnknownHostException The string does not contain a valid address. |
| */ |
| public static Name |
| fromAddress(String addr) throws UnknownHostException { |
| byte [] array = Address.toByteArray(addr, Address.IPv4); |
| if (array == null) |
| array = Address.toByteArray(addr, Address.IPv6); |
| if (array == null) |
| throw new UnknownHostException("Invalid IP address"); |
| return fromAddress(array); |
| } |
| |
| } |