1 files changed, 129 insertions, 0 deletions
diff --git a/libs/minidns/src/main/java/de/measite/minidns/util/NameUtil.java b/libs/minidns/src/main/java/de/measite/minidns/util/NameUtil.java
new file mode 100644
index 00000000..7ae373bc
--- /dev/null
+++ b/libs/minidns/src/main/java/de/measite/minidns/util/NameUtil.java
@@ -0,0 +1,129 @@
+package de.measite.minidns.util;
+
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.net.IDN;
+import java.util.HashSet;
+import java.util.Arrays;
+
+/**
+ * Utilities related to internationalized domain names and dns name handling.
+ */
+public class NameUtil {
+
+    /**
+     * Retrieve the rough binary length of a string
+     * (length + 2 bytes length prefix).
+     * @param name The name string.
+     * @return The binary size of the string (length + 2).
+     */
+    public static int size(String name) {
+        return name.length() + 2;
+    }
+
+    /**
+     * Check if two internationalized domain names are equal, possibly causing
+     * a serialization of both domain names.
+     * @param name1 The first domain name.
+     * @param name2 The second domain name.
+     * @return True if both domain names are the same.
+     */
+    public static boolean idnEquals(String name1, String name2) {
+        if (name1 == name2) return true; // catches null, null
+        if (name1 == null) return false;
+        if (name2 == null) return false;
+        if (name1.equals(name2)) return true;
+
+        try {
+            return Arrays.equals(toByteArray(name1),toByteArray(name2));
+        } catch (IOException e) {
+            return false; // impossible
+        }
+    }
+
+    /**
+     * Serialize a domain name under IDN rules.
+     * @param name The domain name.
+     * @return The binary domain name representation.
+     * @throws IOException Should never happen.
+     */
+    public static byte[] toByteArray(String name) throws IOException {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream(64);
+        DataOutputStream dos = new DataOutputStream(baos);
+        for (String s: name.split("[.\u3002\uFF0E\uFF61]")) {
+            byte[] buffer = IDN.toASCII(s).getBytes();
+            dos.writeByte(buffer.length);
+            dos.write(buffer);
+        }
+        dos.writeByte(0);
+        dos.flush();
+        return baos.toByteArray();
+    }
+
+    /**
+     * Parse a domain name starting at the current offset and moving the input
+     * stream pointer past this domain name (even if cross references occure).
+     * @param dis The input stream.
+     * @param data The raw data (for cross references).
+     * @return The domain name string.
+     * @throws IOException Should never happen.
+     */
+    public static String parse(DataInputStream dis, byte data[]) 
+        throws IOException
+    {
+        int c = dis.readUnsignedByte();
+        if ((c & 0xc0) == 0xc0) {
+            c = ((c & 0x3f) << 8) + dis.readUnsignedByte();
+            HashSet<Integer> jumps = new HashSet<Integer>();
+            jumps.add(c);
+            return parse(data, c, jumps);
+        }
+        if (c == 0) {
+            return "";
+        }
+        byte b[] = new byte[c];
+        dis.readFully(b);
+        String s = IDN.toUnicode(new String(b));
+        String t = parse(dis, data);
+        if (t.length() > 0) {
+            s = s + "." + t;
+        }
+        return s;
+    }
+
+    /**
+     * Parse a domain name starting at the given offset. 
+     * @param data The raw data.
+     * @param offset The offset.
+     * @param jumps The list of jumps (by now).
+     * @return The parsed domain name.
+     * @throws IllegalStateException on cycles.
+     */
+    public static String parse(
+        byte data[],
+        int offset,
+        HashSet<Integer> jumps
+    ) {
+        int c = data[offset] & 0xff;
+        if ((c & 0xc0) == 0xc0) {
+            c = ((c & 0x3f) << 8) + (data[offset + 1] & 0xff);
+            if (jumps.contains(c)) {
+                throw new IllegalStateException("Cyclic offsets detected.");
+            }
+            jumps.add(c);
+            return parse(data, c, jumps);
+        }
+        if (c == 0) {
+            return "";
+        }
+        String s = new String(data,offset + 1, c);
+        String t = parse(data, offset + 1 + c, jumps);
+        if (t.length() > 0) {
+            s = s + "." + t;
+        }
+        return s;
+    }
+
+}