1package eu.siacs.conversations.utils;
2
3import android.content.ContentValues;
4import android.database.Cursor;
5import android.support.annotation.NonNull;
6import android.util.Log;
7
8import java.io.IOException;
9import java.lang.reflect.Field;
10import java.net.Inet4Address;
11import java.net.InetAddress;
12import java.net.UnknownHostException;
13import java.util.ArrayList;
14import java.util.Collections;
15import java.util.List;
16
17import de.measite.minidns.AbstractDNSClient;
18import de.measite.minidns.DNSClient;
19import de.measite.minidns.DNSName;
20import de.measite.minidns.Question;
21import de.measite.minidns.Record;
22import de.measite.minidns.dnssec.DNSSECResultNotAuthenticException;
23import de.measite.minidns.dnsserverlookup.AndroidUsingExec;
24import de.measite.minidns.hla.DnssecResolverApi;
25import de.measite.minidns.hla.ResolverApi;
26import de.measite.minidns.hla.ResolverResult;
27import de.measite.minidns.iterative.ReliableDNSClient;
28import de.measite.minidns.record.A;
29import de.measite.minidns.record.AAAA;
30import de.measite.minidns.record.CNAME;
31import de.measite.minidns.record.Data;
32import de.measite.minidns.record.InternetAddressRR;
33import de.measite.minidns.record.SRV;
34import eu.siacs.conversations.Config;
35import eu.siacs.conversations.R;
36import eu.siacs.conversations.services.XmppConnectionService;
37
38public class Resolver {
39
40 private static final String DIRECT_TLS_SERVICE = "_xmpps-client";
41 private static final String STARTTLS_SERICE = "_xmpp-client";
42
43 private static XmppConnectionService SERVICE = null;
44
45
46 public static void init(XmppConnectionService service) {
47 Resolver.SERVICE = service;
48 DNSClient.removeDNSServerLookupMechanism(AndroidUsingExec.INSTANCE);
49 DNSClient.addDnsServerLookupMechanism(AndroidUsingExecLowPriority.INSTANCE);
50 DNSClient.addDnsServerLookupMechanism(new AndroidUsingLinkProperties(service));
51 final AbstractDNSClient client = ResolverApi.INSTANCE.getClient();
52 if (client instanceof ReliableDNSClient) {
53 disableHardcodedDnsServers((ReliableDNSClient) client);
54 }
55 }
56
57 private static void disableHardcodedDnsServers(ReliableDNSClient reliableDNSClient) {
58 try {
59 final Field dnsClientField = ReliableDNSClient.class.getDeclaredField("dnsClient");
60 dnsClientField.setAccessible(true);
61 final DNSClient dnsClient = (DNSClient) dnsClientField.get(reliableDNSClient);
62 dnsClient.getDataSource().setTimeout(3000);
63 final Field useHardcodedDnsServers = DNSClient.class.getDeclaredField("useHardcodedDnsServers");
64 useHardcodedDnsServers.setAccessible(true);
65 useHardcodedDnsServers.setBoolean(dnsClient, false);
66 } catch (NoSuchFieldException | IllegalAccessException e) {
67 Log.e(Config.LOGTAG, "Unable to disable hardcoded DNS servers", e);
68 }
69 }
70
71 public static List<Result> resolve(String domain) {
72 final List<Result> results = new ArrayList<>();
73 final List<Result> fallbackResults = new ArrayList<>();
74 Thread[] threads = new Thread[3];
75 threads[0] = new Thread(() -> {
76 try {
77 final List<Result> list = resolveSrv(domain, true);
78 synchronized (results) {
79 results.addAll(list);
80 }
81 } catch (Throwable throwable) {
82 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving SRV record (direct TLS)", throwable);
83 }
84 });
85 threads[1] = new Thread(() -> {
86 try {
87 final List<Result> list = resolveSrv(domain, false);
88 synchronized (results) {
89 results.addAll(list);
90 }
91 } catch (Throwable throwable) {
92 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving SRV record (STARTTLS)", throwable);
93 }
94 });
95 threads[2] = new Thread(() -> {
96 List<Result> list = resolveNoSrvRecords(DNSName.from(domain), true);
97 synchronized (fallbackResults) {
98 fallbackResults.addAll(list);
99 }
100 });
101 for (Thread thread : threads) {
102 thread.start();
103 }
104 try {
105 threads[0].join();
106 threads[1].join();
107 if (results.size() > 0) {
108 threads[2].interrupt();
109 Collections.sort(results);
110 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": " + results.toString());
111 return results;
112 } else {
113 threads[2].join();
114 Collections.sort(fallbackResults);
115 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": " + fallbackResults.toString());
116 return fallbackResults;
117 }
118 } catch (InterruptedException e) {
119 return results;
120 }
121 }
122
123 private static List<Result> resolveSrv(String domain, final boolean directTls) throws IOException {
124 DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERICE) + "._tcp." + domain);
125 ResolverResult<SRV> result = resolveWithFallback(dnsName, SRV.class);
126 final List<Result> results = new ArrayList<>();
127 final List<Thread> threads = new ArrayList<>();
128 for (SRV record : result.getAnswersOrEmptySet()) {
129 if (record.name.length() == 0 && record.priority == 0) {
130 continue;
131 }
132 threads.add(new Thread(() -> {
133 final List<Result> ipv4s = resolveIp(record, A.class, result.isAuthenticData(), directTls);
134 if (ipv4s.size() == 0) {
135 Result resolverResult = Result.fromRecord(record, directTls);
136 resolverResult.authenticated = resolverResult.isAuthenticated();
137 ipv4s.add(resolverResult);
138 }
139 synchronized (results) {
140 results.addAll(ipv4s);
141 }
142
143 }));
144 threads.add(new Thread(() -> {
145 final List<Result> ipv6s = resolveIp(record, AAAA.class, result.isAuthenticData(), directTls);
146 synchronized (results) {
147 results.addAll(ipv6s);
148 }
149 }));
150 }
151 for (Thread thread : threads) {
152 thread.start();
153 }
154 for (Thread thread : threads) {
155 try {
156 thread.join();
157 } catch (InterruptedException e) {
158 return Collections.emptyList();
159 }
160 }
161 return results;
162 }
163
164 private static <D extends InternetAddressRR> List<Result> resolveIp(SRV srv, Class<D> type, boolean authenticated, boolean directTls) {
165 List<Result> list = new ArrayList<>();
166 try {
167 ResolverResult<D> results = resolveWithFallback(srv.name, type, authenticated);
168 for (D record : results.getAnswersOrEmptySet()) {
169 Result resolverResult = Result.fromRecord(srv, directTls);
170 resolverResult.authenticated = results.isAuthenticData() && authenticated;
171 resolverResult.ip = record.getInetAddress();
172 list.add(resolverResult);
173 }
174 } catch (Throwable t) {
175 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " " + t.getMessage());
176 }
177 return list;
178 }
179
180 private static List<Result> resolveNoSrvRecords(DNSName dnsName, boolean withCnames) {
181 List<Result> results = new ArrayList<>();
182 try {
183 for (A a : resolveWithFallback(dnsName, A.class, false).getAnswersOrEmptySet()) {
184 results.add(Result.createDefault(dnsName, a.getInetAddress()));
185 }
186 for (AAAA aaaa : resolveWithFallback(dnsName, AAAA.class, false).getAnswersOrEmptySet()) {
187 results.add(Result.createDefault(dnsName, aaaa.getInetAddress()));
188 }
189 if (results.size() == 0 && withCnames) {
190 for (CNAME cname : resolveWithFallback(dnsName, CNAME.class, false).getAnswersOrEmptySet()) {
191 results.addAll(resolveNoSrvRecords(cname.name, false));
192 }
193 }
194 } catch (Throwable throwable) {
195 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + "error resolving fallback records", throwable);
196 }
197 results.add(Result.createDefault(dnsName));
198 return results;
199 }
200
201 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type) throws IOException {
202 return resolveWithFallback(dnsName, type, validateHostname());
203 }
204
205 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type, boolean validateHostname) throws IOException {
206 final Question question = new Question(dnsName, Record.TYPE.getType(type));
207 if (!validateHostname) {
208 return ResolverApi.INSTANCE.resolve(question);
209 }
210 try {
211 return DnssecResolverApi.INSTANCE.resolveDnssecReliable(question);
212 } catch (DNSSECResultNotAuthenticException e) {
213 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", e);
214 } catch (IOException e) {
215 throw e;
216 } catch (Throwable throwable) {
217 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", throwable);
218 }
219 return ResolverApi.INSTANCE.resolve(question);
220 }
221
222 private static boolean validateHostname() {
223 return SERVICE != null && SERVICE.getBooleanPreference("validate_hostname", R.bool.validate_hostname);
224 }
225
226 public static class Result implements Comparable<Result> {
227 public static final String DOMAIN = "domain";
228 public static final String IP = "ip";
229 public static final String HOSTNAME = "hostname";
230 public static final String PORT = "port";
231 public static final String PRIORITY = "priority";
232 public static final String DIRECT_TLS = "directTls";
233 public static final String AUTHENTICATED = "authenticated";
234 private InetAddress ip;
235 private DNSName hostname;
236 private int port = 5222;
237 private boolean directTls = false;
238 private boolean authenticated = false;
239 private int priority;
240
241 static Result fromRecord(SRV srv, boolean directTls) {
242 Result result = new Result();
243 result.port = srv.port;
244 result.hostname = srv.name;
245 result.directTls = directTls;
246 result.priority = srv.priority;
247 return result;
248 }
249
250 static Result createDefault(DNSName hostname, InetAddress ip) {
251 Result result = new Result();
252 result.port = 5222;
253 result.hostname = hostname;
254 result.ip = ip;
255 return result;
256 }
257
258 static Result createDefault(DNSName hostname) {
259 return createDefault(hostname, null);
260 }
261
262 public static Result fromCursor(Cursor cursor) {
263 final Result result = new Result();
264 try {
265 result.ip = InetAddress.getByAddress(cursor.getBlob(cursor.getColumnIndex(IP)));
266 } catch (UnknownHostException e) {
267 result.ip = null;
268 }
269 result.hostname = DNSName.from(cursor.getString(cursor.getColumnIndex(HOSTNAME)));
270 result.port = cursor.getInt(cursor.getColumnIndex(PORT));
271 result.priority = cursor.getInt(cursor.getColumnIndex(PRIORITY));
272 result.authenticated = cursor.getInt(cursor.getColumnIndex(AUTHENTICATED)) > 0;
273 result.directTls = cursor.getInt(cursor.getColumnIndex(DIRECT_TLS)) > 0;
274 return result;
275 }
276
277 @Override
278 public boolean equals(Object o) {
279 if (this == o) return true;
280 if (o == null || getClass() != o.getClass()) return false;
281
282 Result result = (Result) o;
283
284 if (port != result.port) return false;
285 if (directTls != result.directTls) return false;
286 if (authenticated != result.authenticated) return false;
287 if (priority != result.priority) return false;
288 if (ip != null ? !ip.equals(result.ip) : result.ip != null) return false;
289 return hostname != null ? hostname.equals(result.hostname) : result.hostname == null;
290 }
291
292 @Override
293 public int hashCode() {
294 int result = ip != null ? ip.hashCode() : 0;
295 result = 31 * result + (hostname != null ? hostname.hashCode() : 0);
296 result = 31 * result + port;
297 result = 31 * result + (directTls ? 1 : 0);
298 result = 31 * result + (authenticated ? 1 : 0);
299 result = 31 * result + priority;
300 return result;
301 }
302
303 public InetAddress getIp() {
304 return ip;
305 }
306
307 public int getPort() {
308 return port;
309 }
310
311 public DNSName getHostname() {
312 return hostname;
313 }
314
315 public boolean isDirectTls() {
316 return directTls;
317 }
318
319 public boolean isAuthenticated() {
320 return authenticated;
321 }
322
323 @Override
324 public String toString() {
325 return "Result{" +
326 "ip='" + (ip == null ? null : ip.getHostAddress()) + '\'' +
327 ", hostame='" + hostname.toString() + '\'' +
328 ", port=" + port +
329 ", directTls=" + directTls +
330 ", authenticated=" + authenticated +
331 ", priority=" + priority +
332 '}';
333 }
334
335 @Override
336 public int compareTo(@NonNull Result result) {
337 if (result.priority == priority) {
338 if (directTls == result.directTls) {
339 if (ip == null && result.ip == null) {
340 return 0;
341 } else if (ip != null && result.ip != null) {
342 if (ip instanceof Inet4Address && result.ip instanceof Inet4Address) {
343 return 0;
344 } else {
345 return ip instanceof Inet4Address ? -1 : 1;
346 }
347 } else {
348 return ip != null ? -1 : 1;
349 }
350 } else {
351 return directTls ? -1 : 1;
352 }
353 } else {
354 return priority - result.priority;
355 }
356 }
357
358 public ContentValues toContentValues() {
359 final ContentValues contentValues = new ContentValues();
360 contentValues.put(IP, ip == null ? null : ip.getAddress());
361 contentValues.put(HOSTNAME, hostname.toString());
362 contentValues.put(PORT, port);
363 contentValues.put(PRIORITY, priority);
364 contentValues.put(DIRECT_TLS, directTls ? 1 : 0);
365 contentValues.put(AUTHENTICATED, authenticated ? 1 : 0);
366 return contentValues;
367 }
368 }
369
370}