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