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