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