package de.measite.minidns; import java.io.ByteArrayOutputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; import java.util.Arrays; import de.measite.minidns.Record.CLASS; import de.measite.minidns.Record.TYPE; import de.measite.minidns.util.NameUtil; /** * A DNS question (request). */ public class Question { /** * The question string (e.g. "measite.de"). */ private final String name; /** * The question type (e.g. A). */ private final TYPE type; /** * The question class (usually IN / internet). */ private final CLASS clazz; /** * Cache for the serialized object. */ private byte[] byteArray; /** * Create a dns question for the given name/type/class. * @param name The name e.g. "measite.de". * @param type The type, e.g. A. * @param clazz The class, usually IN (internet). */ public Question(String name, TYPE type, CLASS clazz) { this.name = name; this.type = type; this.clazz = clazz; } /** * Create a dns question for the given name/type/IN (internet class). * @param name The name e.g. "measite.de". * @param type The type, e.g. A. */ public Question(String name, TYPE type) { this(name, type, CLASS.IN); } /** * Retrieve the type of this question. * @return The type. */ public TYPE getType() { return type; } /** * Retrieve the class of this dns question (usually internet). * @return The class of this dns question. */ public CLASS getClazz() { return clazz; } /** * Retrieve the name of this dns question (e.g. "measite.de"). * @return The name of this dns question. */ public String getName() { return name; } /** * Parse a byte array and rebuild the dns question from it. * @param dis The input stream. * @param data The plain data (for dns name references). * @return The parsed dns question. * @throws IOException On errors (read outside of packet). */ public static Question parse(DataInputStream dis, byte[] data) throws IOException { String name = NameUtil.parse(dis, data); TYPE type = TYPE.getType(dis.readUnsignedShort()); CLASS clazz = CLASS.getClass(dis.readUnsignedShort()); return new Question (name, type, clazz); } /** * Generate a binary paket for this dns question. * @return The dns question. */ public byte[] toByteArray() { if (byteArray == null) { ByteArrayOutputStream baos = new ByteArrayOutputStream(512); DataOutputStream dos = new DataOutputStream(baos); try { dos.write(NameUtil.toByteArray(this.name)); dos.writeShort(type.getValue()); dos.writeShort(clazz.getValue()); dos.flush(); } catch (IOException e) { // Should never happen throw new IllegalStateException(e); } byteArray = baos.toByteArray(); } return byteArray; } @Override public int hashCode() { return Arrays.hashCode(toByteArray()); } @Override public boolean equals(Object other) { if (this == other) { return true; } if (!(other instanceof Question)) { return false; } byte t[] = toByteArray(); byte o[] = ((Question)other).toByteArray(); return Arrays.equals(t, o); } @Override public String toString() { return "Question/" + clazz + "/" + type + ": " + name; } }