package eu.siacs.conversations.utils; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.util.ArrayList; import java.util.Random; import android.os.Bundle; import android.util.Log; public class DNSHelper { public static Bundle getSRVRecord(String host) throws IOException { InetAddress ip = InetAddress.getByName("8.8.8.8"); try { Class SystemProperties = Class.forName("android.os.SystemProperties"); Method method = SystemProperties.getMethod("get", new Class[] { String.class }); ArrayList servers = new ArrayList(); for (String name : new String[] { "net.dns1", "net.dns2", "net.dns3", "net.dns4", }) { String value = (String) method.invoke(null, name); if (value != null && !"".equals(value) && !servers.contains(value)) ip = InetAddress.getByName(value); servers.add(value); } } catch (ClassNotFoundException e) { ip = InetAddress.getByName("8.8.8.8"); } catch (NoSuchMethodException e) { ip = InetAddress.getByName("8.8.8.8"); } catch (IllegalAccessException e) { ip = InetAddress.getByName("8.8.8.8"); } catch (IllegalArgumentException e) { ip = InetAddress.getByName("8.8.8.8"); } catch (InvocationTargetException e) { ip = InetAddress.getByName("8.8.8.8"); } Log.d("xmppService","using dns server: "+ip.toString()+" to look up SRV records"); Bundle namePort = new Bundle(); String[] hostParts = host.split("\\."); byte[] transId = new byte[2]; Random random = new Random(); random.nextBytes(transId); byte[] header = { 0x01, 0x20, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x0c, 0x5f, 0x78, 0x6d, 0x70, 0x70, 0x2d, 0x63, 0x6c, 0x69, 0x65, 0x6e, 0x74, 0x04, 0x5f, 0x74, 0x63, 0x70 }; byte[] rest = { 0x00, 0x00, 0x21, 0x00, 0x01, 0x00, 0x00, 0x29, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; ByteArrayOutputStream output = new ByteArrayOutputStream(); output.write(transId); output.write(header); for (int i = 0; i < hostParts.length; ++i) { char[] tmpChars = hostParts[i].toCharArray(); byte[] tmp = new byte[tmpChars.length]; for (int j = 0; j < tmpChars.length; ++j) { tmp[j] = (byte) tmpChars[j]; } output.write(tmp.length); output.write(tmp); } output.write(rest); byte[] sendPaket = output.toByteArray(); int realLenght = sendPaket.length - 11; DatagramPacket packet = new DatagramPacket(sendPaket, sendPaket.length, ip, 53); DatagramSocket datagramSocket = new DatagramSocket(); datagramSocket.send(packet); byte[] receiveData = new byte[1024]; DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length); datagramSocket.setSoTimeout(2000); datagramSocket.receive(receivePacket); if (receiveData[3]!=-128) { namePort.putString("error", "nosrv"); return namePort; } namePort.putInt("port",calcPort(receiveData[realLenght + 16], receiveData[realLenght + 17])); int i = realLenght + 18; int wordLenght = 0; StringBuilder builder = new StringBuilder(); while (receiveData[i] != 0) { if (wordLenght > 0) { builder.append((char) receiveData[i]); --wordLenght; } else { wordLenght = receiveData[i]; builder.append("."); } ++i; } builder.replace(0, 1, ""); byte type = receiveData[i+1]; if (type!=-64) { namePort.putString("error", "nosrv"); return namePort; } namePort.putString("name",builder.toString()); return namePort; } static int calcPort(byte hb, byte lb) { int port = ((int) hb << 8) | ((int) lb & 0xFF); if (port>=0) { return port; } else { return 65536 + port; } } final protected static char[] hexArray = "0123456789ABCDEF".toCharArray(); public static String bytesToHex(byte[] bytes) { char[] hexChars = new char[bytes.length * 2]; for ( int j = 0; j < bytes.length; j++ ) { int v = bytes[j] & 0xFF; hexChars[j * 2] = hexArray[v >>> 4]; hexChars[j * 2 + 1] = hexArray[v & 0x0F]; } return new String(hexChars); } }