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.List;
13
14import de.measite.minidns.DNSClient;
15import de.measite.minidns.DNSName;
16import de.measite.minidns.dnssec.DNSSECResultNotAuthenticException;
17import de.measite.minidns.hla.DnssecResolverApi;
18import de.measite.minidns.hla.ResolverApi;
19import de.measite.minidns.hla.ResolverResult;
20import de.measite.minidns.record.A;
21import de.measite.minidns.record.AAAA;
22import de.measite.minidns.record.CNAME;
23import de.measite.minidns.record.Data;
24import de.measite.minidns.record.InternetAddressRR;
25import de.measite.minidns.record.SRV;
26import eu.siacs.conversations.Config;
27
28public class Resolver {
29
30 private static final String DIRECT_TLS_SERVICE = "_xmpps-client";
31 private static final String STARTTLS_SERICE = "_xmpp-client";
32
33
34 public static void registerLookupMechanism(Context context) {
35 DNSClient.addDnsServerLookupMechanism(new AndroidUsingLinkProperties(context));
36 }
37
38 public static List<Result> resolve(String domain) {
39 List<Result> results = new ArrayList<>();
40 try {
41 results.addAll(resolveSrv(domain,true));
42 } catch (IOException e) {
43 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+e.getMessage());
44 }
45 try {
46 results.addAll(resolveSrv(domain,false));
47 } catch (IOException e) {
48 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+e.getMessage());
49 }
50 if (results.size() == 0) {
51 results.addAll(resolveFallback(DNSName.from(domain)));
52 }
53 Collections.sort(results);
54 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+results.toString());
55 return results;
56 }
57
58 private static List<Result> resolveSrv(String domain, final boolean directTls) throws IOException {
59 if (Thread.currentThread().isInterrupted()) {
60 return Collections.emptyList();
61 }
62 DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERICE)+"._tcp."+domain);
63 ResolverResult<SRV> result = resolveWithFallback(dnsName,SRV.class);
64 List<Result> results = new ArrayList<>();
65 for(SRV record : result.getAnswersOrEmptySet()) {
66 final boolean addedIPv4 = results.addAll(resolveIp(record,A.class,result.isAuthenticData(),directTls));
67 results.addAll(resolveIp(record,AAAA.class,result.isAuthenticData(),directTls));
68 if (!addedIPv4 && !Thread.currentThread().isInterrupted()) {
69 Result resolverResult = Result.fromRecord(record, directTls);
70 resolverResult.authenticated = resolverResult.isAuthenticated();
71 results.add(resolverResult);
72 }
73 }
74 return results;
75 }
76
77 private static <D extends InternetAddressRR> List<Result> resolveIp(SRV srv, Class<D> type, boolean authenticated, boolean directTls) {
78 if (Thread.currentThread().isInterrupted()) {
79 return Collections.emptyList();
80 }
81 List<Result> list = new ArrayList<>();
82 try {
83 ResolverResult<D> results = resolveWithFallback(srv.name,type, !authenticated);
84 for (D record : results.getAnswersOrEmptySet()) {
85 Result resolverResult = Result.fromRecord(srv, directTls);
86 resolverResult.authenticated = results.isAuthenticData() && authenticated;
87 resolverResult.ip = record.getInetAddress();
88 list.add(resolverResult);
89 }
90 } catch (Throwable t) {
91 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving "+type.getSimpleName()+" "+t.getMessage());
92 }
93 return list;
94 }
95
96 private static List<Result> resolveFallback(DNSName dnsName) {
97 List<Result> results = new ArrayList<>();
98 try {
99 for(A a : resolveWithFallback(dnsName,A.class,true).getAnswersOrEmptySet()) {
100 results.add(Result.createDefault(dnsName,a.getInetAddress()));
101 }
102 for(AAAA aaaa : resolveWithFallback(dnsName,AAAA.class,true).getAnswersOrEmptySet()) {
103 results.add(Result.createDefault(dnsName,aaaa.getInetAddress()));
104 }
105 if (results.size() == 0) {
106 for (CNAME cname : resolveWithFallback(dnsName, CNAME.class, true).getAnswersOrEmptySet()) {
107 results.addAll(resolveFallback(cname.name));
108 }
109 }
110 } catch (IOException e) {
111 Log.d(Config.LOGTAG,"error resolving fallback records "+e);
112 }
113 if (results.size() == 0) {
114 results.add(Result.createDefault(dnsName));
115 }
116 return results;
117 }
118
119 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type) throws IOException {
120 return resolveWithFallback(dnsName,type,false);
121 }
122
123 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type, boolean skipDnssec) throws IOException {
124 if (skipDnssec) {
125 return ResolverApi.INSTANCE.resolve(dnsName, type);
126 }
127 try {
128 final ResolverResult<D> r = DnssecResolverApi.INSTANCE.resolveDnssecReliable(dnsName, type);
129 if (r.wasSuccessful()) {
130 if (r.getAnswers().isEmpty() && type.equals(SRV.class)) {
131 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": resolving SRV records of " + dnsName.toString() + " with DNSSEC yielded empty result");
132 }
133 return r;
134 }
135 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", r.getResolutionUnsuccessfulException());
136 } catch (DNSSECResultNotAuthenticException e) {
137 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", e);
138 } catch (IOException e) {
139 throw e;
140 } catch (Throwable throwable) {
141 Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", throwable);
142 }
143 return ResolverApi.INSTANCE.resolve(dnsName, type);
144 }
145
146 public static class Result implements Comparable<Result> {
147 private InetAddress ip;
148 private DNSName hostname;
149 private int port = 5222;
150 private boolean directTls = false;
151 private boolean authenticated =false;
152 private int priority;
153
154 public InetAddress getIp() {
155 return ip;
156 }
157
158 public int getPort() {
159 return port;
160 }
161
162 public DNSName getHostname() {
163 return hostname;
164 }
165
166 public boolean isDirectTls() {
167 return directTls;
168 }
169
170 public boolean isAuthenticated() {
171 return authenticated;
172 }
173
174 @Override
175 public String toString() {
176 return "Result{" +
177 "ip='" + (ip==null?null:ip.getHostAddress()) + '\'' +
178 ", hostame='" + hostname.toString() + '\'' +
179 ", port=" + port +
180 ", directTls=" + directTls +
181 ", authenticated=" + authenticated +
182 ", priority=" + priority +
183 '}';
184 }
185
186 @Override
187 public int compareTo(@NonNull Result result) {
188 if (result.priority == priority) {
189 if (directTls == result.directTls) {
190 if (ip == null && result.ip == null) {
191 return 0;
192 } else if (ip != null && result.ip != null) {
193 if (ip instanceof Inet4Address && result.ip instanceof Inet4Address) {
194 return 0;
195 } else {
196 return ip instanceof Inet4Address ? -1 : 1;
197 }
198 } else {
199 return ip != null ? -1 : 1;
200 }
201 } else {
202 return directTls ? -1 : 1;
203 }
204 } else {
205 return priority - result.priority;
206 }
207 }
208
209 public static Result fromRecord(SRV srv, boolean directTls) {
210 Result result = new Result();
211 result.port = srv.port;
212 result.hostname = srv.name;
213 result.directTls = directTls;
214 result.priority = srv.priority;
215 return result;
216 }
217
218 public static Result createDefault(DNSName hostname, InetAddress ip) {
219 Result result = new Result();
220 result.port = 5222;
221 result.hostname = hostname;
222 result.ip = ip;
223 return result;
224 }
225
226 public static Result createDefault(DNSName hostname) {
227 return createDefault(hostname,null);
228 }
229 }
230
231}