1package eu.siacs.conversations.utils;
2
3import android.content.ContentValues;
4import android.database.Cursor;
5import android.util.Log;
6
7import androidx.annotation.NonNull;
8
9import com.google.common.base.Strings;
10import com.google.common.base.Throwables;
11import com.google.common.net.InetAddresses;
12import com.google.common.primitives.Ints;
13
14import java.io.IOException;
15import java.lang.reflect.Field;
16import java.net.Inet4Address;
17import java.net.InetAddress;
18import java.net.UnknownHostException;
19import java.util.ArrayList;
20import java.util.Collections;
21import java.util.List;
22
23import de.gultsch.minidns.AndroidDNSClient;
24import de.measite.minidns.AbstractDNSClient;
25import de.measite.minidns.DNSCache;
26import de.measite.minidns.DNSClient;
27import de.measite.minidns.DNSName;
28import de.measite.minidns.Question;
29import de.measite.minidns.Record;
30import de.measite.minidns.cache.LRUCache;
31import de.measite.minidns.dnssec.DNSSECResultNotAuthenticException;
32import de.measite.minidns.dnsserverlookup.AndroidUsingExec;
33import de.measite.minidns.hla.DnssecResolverApi;
34import de.measite.minidns.hla.ResolverApi;
35import de.measite.minidns.hla.ResolverResult;
36import de.measite.minidns.iterative.ReliableDNSClient;
37import de.measite.minidns.record.A;
38import de.measite.minidns.record.AAAA;
39import de.measite.minidns.record.CNAME;
40import de.measite.minidns.record.Data;
41import de.measite.minidns.record.InternetAddressRR;
42import de.measite.minidns.record.SRV;
43import eu.siacs.conversations.Config;
44import eu.siacs.conversations.R;
45import eu.siacs.conversations.services.XmppConnectionService;
46import eu.siacs.conversations.xmpp.Jid;
47
48public class Resolver {
49
50 public static final int DEFAULT_PORT_XMPP = 5222;
51
52 private static final String DIRECT_TLS_SERVICE = "_xmpps-client";
53 private static final String STARTTLS_SERVICE = "_xmpp-client";
54
55 private static XmppConnectionService SERVICE = null;
56
57
58 public static void init(XmppConnectionService service) {
59 Resolver.SERVICE = service;
60 DNSClient.removeDNSServerLookupMechanism(AndroidUsingExec.INSTANCE);
61 DNSClient.addDnsServerLookupMechanism(AndroidUsingExecLowPriority.INSTANCE);
62 DNSClient.addDnsServerLookupMechanism(new AndroidUsingLinkProperties(service));
63 final AbstractDNSClient client = ResolverApi.INSTANCE.getClient();
64 if (client instanceof ReliableDNSClient) {
65 disableHardcodedDnsServers((ReliableDNSClient) client);
66 }
67 }
68
69 private static void disableHardcodedDnsServers(ReliableDNSClient reliableDNSClient) {
70 try {
71 final Field dnsClientField = ReliableDNSClient.class.getDeclaredField("dnsClient");
72 dnsClientField.setAccessible(true);
73 final DNSClient dnsClient = (DNSClient) dnsClientField.get(reliableDNSClient);
74 if (dnsClient != null) {
75 dnsClient.getDataSource().setTimeout(3000);
76 }
77 final Field useHardcodedDnsServers = DNSClient.class.getDeclaredField("useHardcodedDnsServers");
78 useHardcodedDnsServers.setAccessible(true);
79 useHardcodedDnsServers.setBoolean(dnsClient, false);
80 } catch (NoSuchFieldException | IllegalAccessException e) {
81 Log.e(Config.LOGTAG, "Unable to disable hardcoded DNS servers", e);
82 }
83 }
84
85 public static List<Result> fromHardCoded(final String hostname, final int port) {
86 final Result result = new Result();
87 result.hostname = DNSName.from(hostname);
88 result.port = port;
89 result.directTls = useDirectTls(port);
90 result.authenticated = true;
91 return Collections.singletonList(result);
92 }
93
94 public static void checkDomain(final Jid jid) {
95 DNSName.from(jid.getDomain());
96 }
97
98 public static boolean invalidHostname(final String hostname) {
99 try {
100 DNSName.from(hostname);
101 return false;
102 } catch (IllegalArgumentException e) {
103 return true;
104 }
105 }
106
107 public static void clearCache() {
108 final AbstractDNSClient client = ResolverApi.INSTANCE.getClient();
109 final DNSCache dnsCache = client.getCache();
110 if (dnsCache instanceof LRUCache) {
111 Log.d(Config.LOGTAG,"clearing DNS cache");
112 ((LRUCache) dnsCache).clear();
113 }
114 }
115
116
117 public static boolean useDirectTls(final int port) {
118 return port == 443 || port == 5223;
119 }
120
121 public static List<Result> resolve(final String domain) {
122 final List<Result> ipResults = fromIpAddress(domain);
123 if (ipResults.size() > 0) {
124 return ipResults;
125 }
126 final List<Result> results = new ArrayList<>();
127 final List<Result> fallbackResults = new ArrayList<>();
128 final Thread[] threads = new Thread[3];
129 threads[0] = new Thread(() -> {
130 try {
131 final List<Result> list = resolveSrv(domain, true);
132 synchronized (results) {
133 results.addAll(list);
134 }
135 } catch (final Throwable throwable) {
136 if (!(Throwables.getRootCause(throwable) instanceof InterruptedException)) {
137 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving SRV record (direct TLS)", throwable);
138 }
139 }
140 });
141 threads[1] = new Thread(() -> {
142 try {
143 final List<Result> list = resolveSrv(domain, false);
144 synchronized (results) {
145 results.addAll(list);
146 }
147 } catch (final Throwable throwable) {
148 if (!(Throwables.getRootCause(throwable) instanceof InterruptedException)) {
149 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving SRV record (STARTTLS)", throwable);
150 }
151 }
152 });
153 threads[2] = new Thread(() -> {
154 List<Result> list = resolveNoSrvRecords(DNSName.from(domain), true);
155 synchronized (fallbackResults) {
156 fallbackResults.addAll(list);
157 }
158 });
159 for (final Thread thread : threads) {
160 thread.start();
161 }
162 try {
163 threads[0].join();
164 threads[1].join();
165 if (results.size() > 0) {
166 threads[2].interrupt();
167 synchronized (results) {
168 Collections.sort(results);
169 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": " + results.toString());
170 return new ArrayList<>(results);
171 }
172 } else {
173 threads[2].join();
174 synchronized (fallbackResults) {
175 Collections.sort(fallbackResults);
176 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": " + fallbackResults.toString());
177 return new ArrayList<>(fallbackResults);
178 }
179 }
180 } catch (InterruptedException e) {
181 for (Thread thread : threads) {
182 thread.interrupt();
183 }
184 return Collections.emptyList();
185 }
186 }
187
188 private static List<Result> fromIpAddress(String domain) {
189 if (!IP.matches(domain)) {
190 return Collections.emptyList();
191 }
192 try {
193 Result result = new Result();
194 result.ip = InetAddress.getByName(domain);
195 result.port = DEFAULT_PORT_XMPP;
196 return Collections.singletonList(result);
197 } catch (UnknownHostException e) {
198 return Collections.emptyList();
199 }
200 }
201
202 private static List<Result> resolveSrv(String domain, final boolean directTls) throws IOException {
203 DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERVICE) + "._tcp." + domain);
204 ResolverResult<SRV> result = resolveWithFallback(dnsName, SRV.class);
205 final List<Result> results = new ArrayList<>();
206 final List<Thread> threads = new ArrayList<>();
207 for (SRV record : result.getAnswersOrEmptySet()) {
208 if (record.name.length() == 0 && record.priority == 0) {
209 continue;
210 }
211 threads.add(new Thread(() -> {
212 final List<Result> ipv4s = resolveIp(record, A.class, result.isAuthenticData(), directTls);
213 if (ipv4s.size() == 0) {
214 Result resolverResult = Result.fromRecord(record, directTls);
215 resolverResult.authenticated = result.isAuthenticData();
216 ipv4s.add(resolverResult);
217 }
218 synchronized (results) {
219 results.addAll(ipv4s);
220 }
221
222 }));
223 threads.add(new Thread(() -> {
224 final List<Result> ipv6s = resolveIp(record, AAAA.class, result.isAuthenticData(), directTls);
225 synchronized (results) {
226 results.addAll(ipv6s);
227 }
228 }));
229 }
230 for (Thread thread : threads) {
231 thread.start();
232 }
233 for (Thread thread : threads) {
234 try {
235 thread.join();
236 } catch (InterruptedException e) {
237 return Collections.emptyList();
238 }
239 }
240 return results;
241 }
242
243 private static <D extends InternetAddressRR> List<Result> resolveIp(SRV srv, Class<D> type, boolean authenticated, boolean directTls) {
244 List<Result> list = new ArrayList<>();
245 try {
246 ResolverResult<D> results = resolveWithFallback(srv.name, type, authenticated);
247 for (D record : results.getAnswersOrEmptySet()) {
248 Result resolverResult = Result.fromRecord(srv, directTls);
249 resolverResult.authenticated = results.isAuthenticData() && authenticated; //TODO technically it doesn’t matter if the IP was authenticated
250 resolverResult.ip = record.getInetAddress();
251 list.add(resolverResult);
252 }
253 } catch (Throwable t) {
254 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " " + t.getMessage());
255 }
256 return list;
257 }
258
259 private static List<Result> resolveNoSrvRecords(DNSName dnsName, boolean withCnames) {
260 List<Result> results = new ArrayList<>();
261 try {
262 for (A a : resolveWithFallback(dnsName, A.class, false).getAnswersOrEmptySet()) {
263 results.add(Result.createDefault(dnsName, a.getInetAddress()));
264 }
265 for (AAAA aaaa : resolveWithFallback(dnsName, AAAA.class, false).getAnswersOrEmptySet()) {
266 results.add(Result.createDefault(dnsName, aaaa.getInetAddress()));
267 }
268 if (results.size() == 0 && withCnames) {
269 for (CNAME cname : resolveWithFallback(dnsName, CNAME.class, false).getAnswersOrEmptySet()) {
270 results.addAll(resolveNoSrvRecords(cname.name, false));
271 }
272 }
273 } catch (final Throwable throwable) {
274 if (!(Throwables.getRootCause(throwable) instanceof InterruptedException)) {
275 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + "error resolving fallback records", throwable);
276 }
277 }
278 results.add(Result.createDefault(dnsName));
279 return results;
280 }
281
282 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type) throws IOException {
283 return resolveWithFallback(dnsName, type, validateHostname());
284 }
285
286 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type, boolean validateHostname) throws IOException {
287 final Question question = new Question(dnsName, Record.TYPE.getType(type));
288 if (!validateHostname) {
289 final AndroidDNSClient androidDNSClient = new AndroidDNSClient(SERVICE);
290 final ResolverApi resolverApi = new ResolverApi(androidDNSClient);
291 return resolverApi.resolve(question);
292 }
293 try {
294 return DnssecResolverApi.INSTANCE.resolveDnssecReliable(question);
295 } catch (DNSSECResultNotAuthenticException e) {
296 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", e);
297 } catch (IOException e) {
298 throw e;
299 } catch (Throwable throwable) {
300 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", throwable);
301 }
302 return ResolverApi.INSTANCE.resolve(question);
303 }
304
305 private static boolean validateHostname() {
306 return SERVICE != null && SERVICE.getBooleanPreference("validate_hostname", R.bool.validate_hostname);
307 }
308
309 public static class Result implements Comparable<Result> {
310 public static final String DOMAIN = "domain";
311 public static final String IP = "ip";
312 public static final String HOSTNAME = "hostname";
313 public static final String PORT = "port";
314 public static final String PRIORITY = "priority";
315 public static final String DIRECT_TLS = "directTls";
316 public static final String AUTHENTICATED = "authenticated";
317 private InetAddress ip;
318 private DNSName hostname;
319 private int port = DEFAULT_PORT_XMPP;
320 private boolean directTls = false;
321 private boolean authenticated = false;
322 private int priority;
323
324 static Result fromRecord(SRV srv, boolean directTls) {
325 Result result = new Result();
326 result.port = srv.port;
327 result.hostname = srv.name;
328 result.directTls = directTls;
329 result.priority = srv.priority;
330 return result;
331 }
332
333 static Result createDefault(DNSName hostname, InetAddress ip) {
334 Result result = new Result();
335 result.port = DEFAULT_PORT_XMPP;
336 result.hostname = hostname;
337 result.ip = ip;
338 return result;
339 }
340
341 static Result createDefault(DNSName hostname) {
342 return createDefault(hostname, null);
343 }
344
345 public static Result fromCursor(Cursor cursor) {
346 final Result result = new Result();
347 try {
348 result.ip = InetAddress.getByAddress(cursor.getBlob(cursor.getColumnIndex(IP)));
349 } catch (UnknownHostException e) {
350 result.ip = null;
351 }
352 final String hostname = cursor.getString(cursor.getColumnIndex(HOSTNAME));
353 result.hostname = hostname == null ? null : DNSName.from(hostname);
354 result.port = cursor.getInt(cursor.getColumnIndex(PORT));
355 result.priority = cursor.getInt(cursor.getColumnIndex(PRIORITY));
356 result.authenticated = cursor.getInt(cursor.getColumnIndex(AUTHENTICATED)) > 0;
357 result.directTls = cursor.getInt(cursor.getColumnIndex(DIRECT_TLS)) > 0;
358 return result;
359 }
360
361 @Override
362 public boolean equals(Object o) {
363 if (this == o) return true;
364 if (o == null || getClass() != o.getClass()) return false;
365
366 Result result = (Result) o;
367
368 if (port != result.port) return false;
369 if (directTls != result.directTls) return false;
370 if (authenticated != result.authenticated) return false;
371 if (priority != result.priority) return false;
372 if (ip != null ? !ip.equals(result.ip) : result.ip != null) return false;
373 return hostname != null ? hostname.equals(result.hostname) : result.hostname == null;
374 }
375
376 @Override
377 public int hashCode() {
378 int result = ip != null ? ip.hashCode() : 0;
379 result = 31 * result + (hostname != null ? hostname.hashCode() : 0);
380 result = 31 * result + port;
381 result = 31 * result + (directTls ? 1 : 0);
382 result = 31 * result + (authenticated ? 1 : 0);
383 result = 31 * result + priority;
384 return result;
385 }
386
387 public InetAddress getIp() {
388 return ip;
389 }
390
391 public int getPort() {
392 return port;
393 }
394
395 public DNSName getHostname() {
396 return hostname;
397 }
398
399 public boolean isDirectTls() {
400 return directTls;
401 }
402
403 public boolean isAuthenticated() {
404 return authenticated;
405 }
406
407 @Override
408 public String toString() {
409 return "Result{" +
410 "ip='" + (ip == null ? null : ip.getHostAddress()) + '\'' +
411 ", hostame='" + (hostname == null ? null : hostname.toString()) + '\'' +
412 ", port=" + port +
413 ", directTls=" + directTls +
414 ", authenticated=" + authenticated +
415 ", priority=" + priority +
416 '}';
417 }
418
419 @Override
420 public int compareTo(@NonNull Result result) {
421 if (result.priority == priority) {
422 if (directTls == result.directTls) {
423 if (ip == null && result.ip == null) {
424 return 0;
425 } else if (ip != null && result.ip != null) {
426 if (ip instanceof Inet4Address && result.ip instanceof Inet4Address) {
427 return 0;
428 } else {
429 return ip instanceof Inet4Address ? -1 : 1;
430 }
431 } else {
432 return ip != null ? -1 : 1;
433 }
434 } else {
435 return directTls ? -1 : 1;
436 }
437 } else {
438 return priority - result.priority;
439 }
440 }
441
442 public ContentValues toContentValues() {
443 final ContentValues contentValues = new ContentValues();
444 contentValues.put(IP, ip == null ? null : ip.getAddress());
445 contentValues.put(HOSTNAME, hostname == null ? null : hostname.toString());
446 contentValues.put(PORT, port);
447 contentValues.put(PRIORITY, priority);
448 contentValues.put(DIRECT_TLS, directTls ? 1 : 0);
449 contentValues.put(AUTHENTICATED, authenticated ? 1 : 0);
450 return contentValues;
451 }
452
453 public Result seeOtherHost(final String seeOtherHost) {
454 final String hostname = seeOtherHost.trim();
455 if (hostname.isEmpty()) {
456 return null;
457 }
458 final Result result = new Result();
459 result.directTls = this.directTls;
460 final int portSegmentStart = hostname.lastIndexOf(':');
461 if (hostname.charAt(hostname.length() - 1) != ']'
462 && portSegmentStart >= 0
463 && hostname.length() >= portSegmentStart + 1) {
464 final String hostPart = hostname.substring(0, portSegmentStart);
465 final String portPart = hostname.substring(portSegmentStart + 1);
466 final Integer port = Ints.tryParse(portPart);
467 if (port == null || Strings.isNullOrEmpty(hostPart)) {
468 return null;
469 }
470 final String host = eu.siacs.conversations.utils.IP.unwrapIPv6(hostPart);
471 result.port = port;
472 if (InetAddresses.isInetAddress(host)) {
473 final InetAddress inetAddress;
474 try {
475 inetAddress = InetAddresses.forString(host);
476 } catch (final IllegalArgumentException e) {
477 return null;
478 }
479 result.ip = inetAddress;
480 } else {
481 if (hostPart.trim().isEmpty()) {
482 return null;
483 }
484 try {
485 result.hostname = DNSName.from(hostPart.trim());
486 } catch (final Exception e) {
487 return null;
488 }
489 }
490 } else {
491 final String host = eu.siacs.conversations.utils.IP.unwrapIPv6(hostname);
492 if (InetAddresses.isInetAddress(host)) {
493 final InetAddress inetAddress;
494 try {
495 inetAddress = InetAddresses.forString(host);
496 } catch (final IllegalArgumentException e) {
497 return null;
498 }
499 result.ip = inetAddress;
500 } else {
501 try {
502 result.hostname = DNSName.from(hostname);
503 } catch (final Exception e) {
504 return null;
505 }
506 }
507 result.port = port;
508 }
509 return result;
510 }
511 }
512
513}