PairingServer.java

/*
 * Copyright (C) 2008 Jeffrey Sharkey, http://jsharkey.org/ This program is free
 * software: you can redistribute it and/or modify it under the terms of the GNU
 * General Public License as published by the Free Software Foundation, either
 * version 3 of the License, or (at your option) any later version. This program
 * is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE. See the GNU General Public License for more details. You
 * should have received a copy of the GNU General Public License along with this
 * program. If not, see <http://www.gnu.org/licenses/>.
 */

package org.tunescontrol.daap;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Random;

import android.os.Handler;
import android.os.Message;
import android.util.Log;

public class PairingServer extends Thread {

   // the pairing service waits for any incoming requests from itunes
   // it always returns a valid pairing code
   public final static String TAG = PairingServer.class.toString();
   public final static int PORT = 1024;

   protected final static byte[] CHAR_TABLE = new byte[] { (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F' };

   public static byte[] PAIRING_RAW = new byte[] { 0x63, 0x6d, 0x70, 0x61, 0x00, 0x00, 0x00, 0x3a, 0x63, 0x6d, 0x70, 0x67, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x63, 0x6d, 0x6e, 0x6d, 0x00, 0x00, 0x00, 0x16, 0x41, 0x64, 0x6d, 0x69, 0x6e, 0x69, 0x73, 0x74, 0x72,
            0x61, 0x74, 0x6f, 0x72, (byte) 0xe2, (byte) 0x80, (byte) 0x99, 0x73, 0x20, 0x69, 0x50, 0x6f, 0x64, 0x63, 0x6d, 0x74, 0x79, 0x00, 0x00, 0x00, 0x04, 0x69, 0x50, 0x6f, 0x64 };

   // this is a hack so that we always return to the "latest" handler
   protected static Handler paired;

   protected ServerSocket server;
   protected final Random random = new Random();

   public PairingServer(Handler paired) {
      PairingServer.paired = paired;
   }

   public void destroy() {
      Log.d(TAG, "Destroying PairingServer " + PORT);
      try {
         if ((this.server != null) && (!this.server.isClosed())) {
            Log.i(TAG, "Destroying Socket " + PORT);
            this.server.close();
            this.server = null;
         }
         this.interrupt();
      } catch (IOException e) {
         Log.w(TAG, e);
      }
   }

   public void run() {
      try {
         // start listening on a specific port for any requests
         Log.i(TAG, "Starting Socket Server on Port " + PORT);
         this.server = new ServerSocket(PORT);

         Thread thisThread = Thread.currentThread();

         while (this == thisThread) {
            if (server.isClosed()) {
               // break out of the thread loop if server is closed
               break;
            }

            // start accepting data on incoming socket
            final Socket socket = server.accept();

            // we dont care about checking the incoming pairing md5 from itunes
            // and we always just accept the pairing
            OutputStream output = null;

            try {
               output = socket.getOutputStream();

               // output the contents for debugging
               final BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
               while (br.ready()) {
                  String line = br.readLine();
                  Log.d(TAG, line);
               }

               // edit our local PAIRING_RAW to return the correct guid
               byte[] code = new byte[8];
               random.nextBytes(code);
               System.arraycopy(code, 0, PAIRING_RAW, 16, 8);
               String niceCode = toHex(code);

               byte[] header = String.format("HTTP/1.1 200 OK\r\nContent-Length: %d\r\n\r\n", PAIRING_RAW.length).getBytes();
               byte[] reply = new byte[header.length + PAIRING_RAW.length];

               System.arraycopy(header, 0, reply, 0, header.length);
               System.arraycopy(PAIRING_RAW, 0, reply, header.length, PAIRING_RAW.length);

               output.write(reply);

               Log.i(TAG, "someone paired with me!");

               // trigger a handler that says weve been paired pass back the
               // random code we generated
               paired.sendMessage(Message.obtain(paired, -1, niceCode));

            } finally {
               if (output != null) {
                  output.flush();
                  output.close();
               }

               Log.i(TAG, "Closing Socket " + PORT);
               if ((this.server != null) && (!this.server.isClosed())) {
                  this.server.close();
               }
            }
         }

         Log.i(TAG, "PairingServer thread stopped...");
      } catch (IOException e) {
         Log.w(TAG, e);
      }

   }

   private static String toHex(byte[] code) {
      // somewhat borrowed from rgagnon.com
      byte[] result = new byte[2 * code.length];
      int index = 0;
      for (byte b : code) {
         int v = b & 0xff;
         result[index++] = CHAR_TABLE[v >>> 4];
         result[index++] = CHAR_TABLE[v & 0xf];
      }
      return new String(result);
   }

}