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package eu.siacs.conversations.utils;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Random;
import android.os.Bundle;
public class DNSHelper {
public static Bundle getSRVRecord(String host) throws IOException {
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();
byte[] addr = { 0x8, 0x8, 0x8, 0x8 };
int realLenght = sendPaket.length - 11;
DatagramPacket packet = new DatagramPacket(sendPaket,
sendPaket.length, InetAddress.getByAddress(addr), 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, "");
namePort.putString("name",builder.toString());
return namePort;
}
static int calcPort(byte hb, byte lb) {
return ((int) hb << 8) | ((int) lb & 0xFF);
}
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);
}
}
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