1 files changed, 130 insertions, 0 deletions
diff --git a/src/org/xbill/DNS/ReverseMap.java b/src/org/xbill/DNS/ReverseMap.java
new file mode 100644
index 0000000..f4293de
--- /dev/null
+++ b/src/org/xbill/DNS/ReverseMap.java
@@ -0,0 +1,130 @@
+// 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);
+}
+
+}