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package eu.siacs.conversations.utils;
import de.measite.minidns.Client;
import de.measite.minidns.DNSMessage;
import de.measite.minidns.Record;
import de.measite.minidns.Record.TYPE;
import de.measite.minidns.Record.CLASS;
import de.measite.minidns.record.SRV;
import de.measite.minidns.record.A;
import de.measite.minidns.record.AAAA;
import de.measite.minidns.record.Data;
import de.measite.minidns.util.NameUtil;
import eu.siacs.conversations.Config;
import java.io.IOException;
import java.net.InetAddress;
import java.net.SocketTimeoutException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;
import java.util.TreeMap;
import android.os.Bundle;
import android.util.Log;
public class DNSHelper {
protected static Client client = new Client();
public static Bundle getSRVRecord(String host) throws IOException {
String dns[] = client.findDNS();
if (dns != null) {
// we have a list of DNS servers, let's go
for (String dnsserver : dns) {
InetAddress ip = InetAddress.getByName(dnsserver);
Bundle b = queryDNS(host, ip);
if (b.containsKey("name")) {
return b;
}
}
}
// fallback
return queryDNS(host, InetAddress.getByName("8.8.8.8"));
}
public static Bundle queryDNS(String host, InetAddress dnsServer) {
Bundle namePort = new Bundle();
try {
String qname = "_xmpp-client._tcp." + host;
Log.d(Config.LOGTAG,
"using dns server: " + dnsServer.getHostAddress()
+ " to look up " + host);
DNSMessage message = client.query(qname, TYPE.SRV, CLASS.IN,
dnsServer.getHostAddress());
// How should we handle priorities and weight?
// Wikipedia has a nice article about priorities vs. weights:
// https://en.wikipedia.org/wiki/SRV_record#Provisioning_for_high_service_availability
// we bucket the SRV records based on priority, pick per priority
// a random order respecting the weight, and dump that priority by
// priority
TreeMap<Integer, ArrayList<SRV>> priorities = new TreeMap<Integer, ArrayList<SRV>>();
TreeMap<String, ArrayList<String>> ips4 = new TreeMap<String, ArrayList<String>>();
TreeMap<String, ArrayList<String>> ips6 = new TreeMap<String, ArrayList<String>>();
for (Record[] rrset : new Record[][] { message.getAnswers(),
message.getAdditionalResourceRecords() }) {
for (Record rr : rrset) {
Data d = rr.getPayload();
if (d instanceof SRV
&& NameUtil.idnEquals(qname, rr.getName())) {
SRV srv = (SRV) d;
if (!priorities.containsKey(srv.getPriority())) {
priorities.put(srv.getPriority(),
new ArrayList<SRV>(2));
}
priorities.get(srv.getPriority()).add(srv);
}
if (d instanceof A) {
A arecord = (A) d;
if (!ips4.containsKey(rr.getName())) {
ips4.put(rr.getName(), new ArrayList<String>(3));
}
ips4.get(rr.getName()).add(arecord.toString());
}
if (d instanceof AAAA) {
AAAA aaaa = (AAAA) d;
if (!ips6.containsKey(rr.getName())) {
ips6.put(rr.getName(), new ArrayList<String>(3));
}
ips6.get(rr.getName()).add("[" + aaaa.toString() + "]");
}
}
}
Random rnd = new Random();
ArrayList<SRV> result = new ArrayList<SRV>(
priorities.size() * 2 + 1);
for (ArrayList<SRV> s : priorities.values()) {
// trivial case
if (s.size() <= 1) {
result.addAll(s);
continue;
}
long totalweight = 0l;
for (SRV srv : s) {
totalweight += srv.getWeight();
}
while (totalweight > 0l && s.size() > 0) {
long p = (rnd.nextLong() & 0x7fffffffffffffffl)
% totalweight;
int i = 0;
while (p > 0) {
p -= s.get(i++).getPriority();
}
i--;
// remove is expensive, but we have only a few entries
// anyway
SRV srv = s.remove(i);
totalweight -= srv.getWeight();
result.add(srv);
}
Collections.shuffle(s, rnd);
result.addAll(s);
}
if (result.size() == 0) {
namePort.putString("error", "nosrv");
return namePort;
}
// we now have a list of servers to try :-)
// classic name/port pair
String resultName = result.get(0).getName();
namePort.putString("name", resultName);
namePort.putInt("port", result.get(0).getPort());
if (ips4.containsKey(resultName)) {
// we have an ip!
ArrayList<String> ip = ips4.get(resultName);
Collections.shuffle(ip, rnd);
namePort.putString("ipv4", ip.get(0));
}
if (ips6.containsKey(resultName)) {
ArrayList<String> ip = ips6.get(resultName);
Collections.shuffle(ip, rnd);
namePort.putString("ipv6", ip.get(0));
}
// add all other records
int i = 0;
for (SRV srv : result) {
namePort.putString("name" + i, srv.getName());
namePort.putInt("port" + i, srv.getPort());
i++;
}
} catch (SocketTimeoutException e) {
Log.d(Config.LOGTAG, "timeout during dns");
namePort.putString("error", "timeout");
} catch (Exception e) {
Log.d(Config.LOGTAG, "unhandled exception in sub project");
namePort.putString("error", "unhandled");
}
return namePort;
}
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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