1package eu.siacs.conversations.utils;
2
3import android.content.Context;
4import android.support.annotation.NonNull;
5import android.util.Log;
6
7import java.io.IOException;
8import java.net.Inet4Address;
9import java.net.InetAddress;
10import java.util.ArrayList;
11import java.util.Collections;
12import java.util.HashSet;
13import java.util.List;
14
15import de.measite.minidns.DNSClient;
16import de.measite.minidns.DNSName;
17import de.measite.minidns.Question;
18import de.measite.minidns.Record;
19import de.measite.minidns.dnssec.DNSSECResultNotAuthenticException;
20import de.measite.minidns.dnsserverlookup.AndroidUsingExec;
21import de.measite.minidns.hla.DnssecResolverApi;
22import de.measite.minidns.hla.ResolverApi;
23import de.measite.minidns.hla.ResolverResult;
24import de.measite.minidns.record.A;
25import de.measite.minidns.record.AAAA;
26import de.measite.minidns.record.CNAME;
27import de.measite.minidns.record.Data;
28import de.measite.minidns.record.InternetAddressRR;
29import de.measite.minidns.record.SRV;
30import de.measite.minidns.util.MultipleIoException;
31import eu.siacs.conversations.Config;
32import eu.siacs.conversations.R;
33import eu.siacs.conversations.services.XmppConnectionService;
34
35public class Resolver {
36
37 private static final String DIRECT_TLS_SERVICE = "_xmpps-client";
38 private static final String STARTTLS_SERICE = "_xmpp-client";
39
40 private static final String NETWORK_IS_UNREACHABLE = "Network is unreachable";
41
42 private static XmppConnectionService SERVICE = null;
43
44
45 public static void init(XmppConnectionService service) {
46 Resolver.SERVICE = service;
47 DNSClient.removeDNSServerLookupMechanism(AndroidUsingExec.INSTANCE);
48 DNSClient.addDnsServerLookupMechanism(AndroidUsingExecLowPriority.INSTANCE);
49 DNSClient.addDnsServerLookupMechanism(new AndroidUsingLinkProperties(service));
50 }
51
52 public static List<Result> resolve(String domain) throws NetworkIsUnreachableException {
53 List<Result> results = new ArrayList<>();
54 HashSet<String> messages = new HashSet<>();
55 try {
56 results.addAll(resolveSrv(domain, true));
57 } catch (MultipleIoException e) {
58 messages.addAll(extractMessages(e));
59 } catch (Throwable throwable) {
60 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving SRV record (direct TLS)",throwable);
61 }
62 try {
63 results.addAll(resolveSrv(domain, false));
64 } catch (MultipleIoException e) {
65 messages.addAll(extractMessages(e));
66 } catch (Throwable throwable) {
67 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving SRV record (STARTTLS)",throwable);
68 }
69 if (results.size() == 0) {
70 if (messages.size() == 1 && messages.contains(NETWORK_IS_UNREACHABLE)) {
71 throw new NetworkIsUnreachableException();
72 }
73 results.addAll(resolveNoSrvRecords(DNSName.from(domain),true));
74 }
75 Collections.sort(results);
76 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+results.toString());
77 return results;
78 }
79
80 private static HashSet<String> extractMessages(MultipleIoException e) {
81 HashSet<String> messages = new HashSet<>();
82 for(Exception inner : e.getExceptions()) {
83 if (inner instanceof MultipleIoException) {
84 messages.addAll(extractMessages((MultipleIoException) inner));
85 } else {
86 messages.add(inner.getMessage());
87 }
88 }
89 return messages;
90 }
91
92 private static List<Result> resolveSrv(String domain, final boolean directTls) throws IOException {
93 if (Thread.currentThread().isInterrupted()) {
94 return Collections.emptyList();
95 }
96 DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERICE)+"._tcp."+domain);
97 ResolverResult<SRV> result = resolveWithFallback(dnsName,SRV.class);
98 List<Result> results = new ArrayList<>();
99 for(SRV record : result.getAnswersOrEmptySet()) {
100 final boolean addedIPv4 = results.addAll(resolveIp(record,A.class,result.isAuthenticData(),directTls));
101 results.addAll(resolveIp(record,AAAA.class,result.isAuthenticData(),directTls));
102 if (!addedIPv4 && !Thread.currentThread().isInterrupted()) {
103 Result resolverResult = Result.fromRecord(record, directTls);
104 resolverResult.authenticated = resolverResult.isAuthenticated();
105 results.add(resolverResult);
106 }
107 }
108 return results;
109 }
110
111 private static <D extends InternetAddressRR> List<Result> resolveIp(SRV srv, Class<D> type, boolean authenticated, boolean directTls) {
112 if (Thread.currentThread().isInterrupted()) {
113 return Collections.emptyList();
114 }
115 List<Result> list = new ArrayList<>();
116 try {
117 ResolverResult<D> results = resolveWithFallback(srv.name,type, authenticated);
118 for (D record : results.getAnswersOrEmptySet()) {
119 Result resolverResult = Result.fromRecord(srv, directTls);
120 resolverResult.authenticated = results.isAuthenticData() && authenticated;
121 resolverResult.ip = record.getInetAddress();
122 list.add(resolverResult);
123 }
124 } catch (Throwable t) {
125 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving "+type.getSimpleName()+" "+t.getMessage());
126 }
127 return list;
128 }
129
130 private static List<Result> resolveNoSrvRecords(DNSName dnsName, boolean withCnames) {
131 List<Result> results = new ArrayList<>();
132 try {
133 for(A a : resolveWithFallback(dnsName,A.class,false).getAnswersOrEmptySet()) {
134 results.add(Result.createDefault(dnsName,a.getInetAddress()));
135 }
136 for(AAAA aaaa : resolveWithFallback(dnsName,AAAA.class,false).getAnswersOrEmptySet()) {
137 results.add(Result.createDefault(dnsName,aaaa.getInetAddress()));
138 }
139 if (results.size() == 0 && withCnames) {
140 for (CNAME cname : resolveWithFallback(dnsName, CNAME.class, false).getAnswersOrEmptySet()) {
141 results.addAll(resolveNoSrvRecords(cname.name, false));
142 }
143 }
144 } catch (Throwable throwable) {
145 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + "error resolving fallback records",throwable);
146 }
147 results.add(Result.createDefault(dnsName));
148 return results;
149 }
150
151 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type) throws IOException {
152 return resolveWithFallback(dnsName,type,validateHostname());
153 }
154
155 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type, boolean validateHostname) throws IOException {
156 final Question question = new Question(dnsName, Record.TYPE.getType(type));
157 if (!validateHostname) {
158 return ResolverApi.INSTANCE.resolve(question);
159 }
160 try {
161 return DnssecResolverApi.INSTANCE.resolveDnssecReliable(question);
162 } catch (DNSSECResultNotAuthenticException e) {
163 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", e);
164 } catch (IOException e) {
165 throw e;
166 } catch (Throwable throwable) {
167 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", throwable);
168 }
169 return ResolverApi.INSTANCE.resolve(question);
170 }
171
172 private static boolean validateHostname() {
173 return SERVICE != null && SERVICE.getBooleanPreference("validate_hostname", R.bool.validate_hostname);
174 }
175
176 public static class Result implements Comparable<Result> {
177 private InetAddress ip;
178 private DNSName hostname;
179 private int port = 5222;
180 private boolean directTls = false;
181 private boolean authenticated =false;
182 private int priority;
183
184 public InetAddress getIp() {
185 return ip;
186 }
187
188 public int getPort() {
189 return port;
190 }
191
192 public DNSName getHostname() {
193 return hostname;
194 }
195
196 public boolean isDirectTls() {
197 return directTls;
198 }
199
200 public boolean isAuthenticated() {
201 return authenticated;
202 }
203
204 @Override
205 public String toString() {
206 return "Result{" +
207 "ip='" + (ip==null?null:ip.getHostAddress()) + '\'' +
208 ", hostame='" + hostname.toString() + '\'' +
209 ", port=" + port +
210 ", directTls=" + directTls +
211 ", authenticated=" + authenticated +
212 ", priority=" + priority +
213 '}';
214 }
215
216 @Override
217 public int compareTo(@NonNull Result result) {
218 if (result.priority == priority) {
219 if (directTls == result.directTls) {
220 if (ip == null && result.ip == null) {
221 return 0;
222 } else if (ip != null && result.ip != null) {
223 if (ip instanceof Inet4Address && result.ip instanceof Inet4Address) {
224 return 0;
225 } else {
226 return ip instanceof Inet4Address ? -1 : 1;
227 }
228 } else {
229 return ip != null ? -1 : 1;
230 }
231 } else {
232 return directTls ? -1 : 1;
233 }
234 } else {
235 return priority - result.priority;
236 }
237 }
238
239 public static Result fromRecord(SRV srv, boolean directTls) {
240 Result result = new Result();
241 result.port = srv.port;
242 result.hostname = srv.name;
243 result.directTls = directTls;
244 result.priority = srv.priority;
245 return result;
246 }
247
248 public static Result createDefault(DNSName hostname, InetAddress ip) {
249 Result result = new Result();
250 result.port = 5222;
251 result.hostname = hostname;
252 result.ip = ip;
253 return result;
254 }
255
256 public static Result createDefault(DNSName hostname) {
257 return createDefault(hostname,null);
258 }
259 }
260 public static class NetworkIsUnreachableException extends Exception {
261
262 }
263
264}