Merge pull request #39 from rtreffer/minidns
Switch to a small DNS library for DNS resolving.
This commit is contained in:
Daniel Gultsch
commit
2efb97efa0
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@ -1,3 +1,7 @@
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[submodule "libs/openpgp-keychain"]
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path = libs/openpgp-keychain
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url = https://github.com/openpgp-keychain/openpgp-keychain.git
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[submodule "libs/minidns"]
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path = libs/minidns
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url = https://github.com/rtreffer/minidns.git
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@ -0,0 +1 @@
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Subproject commit d5cca3b3a48cfaed3008050fcab9574d97d771cc
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@ -13,3 +13,4 @@
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# Project target.
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target=android-19
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android.library.reference.1=libs/openpgp-keychain/OpenPGP-Keychain-API/libraries/openpgp-api-library
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android.library.reference.2=libs/minidns
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@ -1,125 +1,134 @@
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package eu.siacs.conversations.utils;
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import java.io.ByteArrayOutputStream;
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import de.measite.minidns.Client;
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import de.measite.minidns.DNSMessage;
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import de.measite.minidns.Record;
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import de.measite.minidns.Record.TYPE;
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import de.measite.minidns.Record.CLASS;
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import de.measite.minidns.record.SRV;
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import de.measite.minidns.record.Data;
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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.Collections;
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import java.util.Random;
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import java.util.TreeMap;
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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
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.forName("android.os.SystemProperties");
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Method method = SystemProperties.getMethod("get",
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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",
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"net.dns3", "net.dns4", }) {
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String value = (String) method.invoke(null, name);
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protected static Client client = new Client();
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if (value != null && !"".equals(value)
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&& !servers.contains(value)) {
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ip = InetAddress.getByName(value);
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servers.add(value);
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Bundle result = queryDNS(host, ip);
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if (!result.containsKey("error")||("nosrv".equals(result.getString("error")))) {
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return result;
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public static Bundle getSRVRecord(String host) throws IOException {
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String dns[] = client.findDNS();
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if (dns != null) {
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// we have a list of DNS servers, let's go
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for (String dnsserver : dns) {
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InetAddress ip = InetAddress.getByName(dnsserver);
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Bundle b = queryDNS(host, ip);
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if (b.containsKey("name")) {
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return b;
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}
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}
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}
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} catch (Exception e) {
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Log.d("xmppService","error during system calls");
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}
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ip = InetAddress.getByName("8.8.8.8");
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return queryDNS(host, ip);
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// fallback
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return queryDNS(host, InetAddress.getByName("8.8.8.8"));
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}
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public static Bundle queryDNS(String host, InetAddress dnsServer) {
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Bundle namePort = new Bundle();
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try {
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Log.d("xmppService", "using dns server: " + dnsServer.toString()
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Log.d("xmppService", "using dns server: " + dnsServer.getHostAddress()
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+ " to look up " + host);
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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, dnsServer, 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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DNSMessage message =
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client.query(
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"_xmpp-client._tcp." + host,
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TYPE.SRV,
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CLASS.IN,
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dnsServer.getHostAddress());
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DatagramPacket receivePacket = new DatagramPacket(receiveData,
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receiveData.length);
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datagramSocket.setSoTimeout(7000); //die sieben ist meine zahl
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datagramSocket.receive(receivePacket);
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if (receiveData[3] != -128) {
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// How should we handle priorities and weight?
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// Wikipedia has a nice article about priorities vs. weights:
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// https://en.wikipedia.org/wiki/SRV_record#Provisioning_for_high_service_availability
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// we bucket the SRV records based on priority, pick per priority
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// a random order respecting the weight, and dump that priority by
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// priority
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TreeMap<Integer, ArrayList<SRV>> priorities =
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new TreeMap<Integer, ArrayList<SRV>>();
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for (Record rr : message.getAnswers()) {
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Data d = rr.getPayload();
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if (d instanceof SRV) {
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SRV srv = (SRV) d;
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if (!priorities.containsKey(srv.getPriority())) {
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priorities.put(srv.getPriority(), new ArrayList<SRV>(2));
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}
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priorities.get(srv.getPriority()).add(srv);
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}
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}
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Random rnd = new Random();
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ArrayList<SRV> result = new ArrayList<SRV>(priorities.size() * 2 + 1);
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for (ArrayList<SRV> s: priorities.values()) {
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// trivial case
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if (s.size() <= 1) {
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result.addAll(s);
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continue;
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}
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long totalweight = 0l;
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for (SRV srv: s) {
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totalweight += srv.getWeight();
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}
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while (totalweight > 0l && s.size() > 0) {
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long p = (rnd.nextLong() & 0x7fffffffffffffffl) % totalweight;
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int i = 0;
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while (p > 0) {
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p -= s.get(i++).getPriority();
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}
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i--;
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// remove is expensive, but we have only a few entries anyway
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SRV srv = s.remove(i);
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totalweight -= srv.getWeight();
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result.add(srv);
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}
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Collections.shuffle(s, rnd);
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result.addAll(s);
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}
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if (result.size() == 0) {
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namePort.putString("error", "nosrv");
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return namePort;
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}
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namePort.putInt(
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"port",
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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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byte type = receiveData[i + 1];
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byte type2 = receiveData[i + 2];
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if ((type == -64) || (type == type2)) {
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namePort.putString("name", builder.toString());
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return namePort;
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} else {
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Log.d("xmppService", "type=" + type + " type2=" + type2 + " "
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+ builder.toString());
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namePort.putString("error", "nosrv");
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return namePort;
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// we now have a list of servers to try :-)
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// classic name/port pair
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namePort.putString("name", result.get(0).getName());
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namePort.putInt("port", result.get(0).getPort());
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// add all other records
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int i = 0;
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for (SRV srv : result) {
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namePort.putString("name" + i, srv.getName());
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namePort.putInt("port" + i, srv.getPort());
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i++;
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}
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} catch (IOException e) {
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Log.d("xmppService", "io execpiton during dns");
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Log.e("xmppService", "io execpiton during dns", e);
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namePort.putString("error", "timeout");
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return namePort;
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}
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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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