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.InetAddress;
9import java.util.ArrayList;
10import java.util.Collections;
11import java.util.List;
12
13import de.measite.minidns.DNSClient;
14import de.measite.minidns.DNSName;
15import de.measite.minidns.dnssec.DNSSECResultNotAuthenticException;
16import de.measite.minidns.hla.DnssecResolverApi;
17import de.measite.minidns.hla.ResolverApi;
18import de.measite.minidns.hla.ResolverResult;
19import de.measite.minidns.record.A;
20import de.measite.minidns.record.AAAA;
21import de.measite.minidns.record.Data;
22import de.measite.minidns.record.InternetAddressRR;
23import de.measite.minidns.record.SRV;
24import eu.siacs.conversations.Config;
25
26public class Resolver {
27
28 private static final String DIRECT_TLS_SERVICE = "_xmpps-client";
29 private static final String STARTTLS_SERICE = "_xmpp-client";
30
31
32 public static void registerLookupMechanism(Context context) {
33 DNSClient.addDnsServerLookupMechanism(new AndroidUsingLinkProperties(context));
34 }
35
36 public static List<Result> resolve(String domain) {
37 List<Result> results = new ArrayList<>();
38 try {
39 results.addAll(resolveSrv(domain,true));
40 } catch (IOException e) {
41 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+e.getMessage());
42 }
43 try {
44 results.addAll(resolveSrv(domain,false));
45 } catch (IOException e) {
46 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+e.getMessage());
47 }
48 if (results.size() == 0) {
49 results.add(Result.createDefault(domain));
50 }
51 Collections.sort(results);
52 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+results.toString());
53 return results;
54 }
55
56 private static List<Result> resolveSrv(String domain, final boolean directTls) throws IOException {
57 if (Thread.interrupted()) {
58 return Collections.emptyList();
59 }
60 DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERICE)+"._tcp."+domain);
61 ResolverResult<SRV> result = resolveWithFallback(dnsName,SRV.class);
62 List<Result> results = new ArrayList<>();
63 for(SRV record : result.getAnswersOrEmptySet()) {
64 final boolean addedIPv4 = results.addAll(resolveIp(record,A.class,result.isAuthenticData(),directTls));
65 results.addAll(resolveIp(record,AAAA.class,result.isAuthenticData(),directTls));
66 if (!addedIPv4 && !Thread.interrupted()) {
67 Result resolverResult = Result.fromRecord(record, directTls);
68 resolverResult.authenticated = resolverResult.isAuthenticated();
69 results.add(resolverResult);
70 }
71 }
72 return results;
73 }
74
75 private static <D extends InternetAddressRR> List<Result> resolveIp(SRV srv, Class<D> type, boolean authenticated, boolean directTls) {
76 if (Thread.interrupted()) {
77 return Collections.emptyList();
78 }
79 List<Result> list = new ArrayList<>();
80 try {
81 ResolverResult<D> results = resolveWithFallback(srv.name,type);
82 for (D record : results.getAnswersOrEmptySet()) {
83 Result resolverResult = Result.fromRecord(srv, directTls);
84 resolverResult.authenticated = results.isAuthenticData() && authenticated;
85 resolverResult.ip = record.getInetAddress();
86 list.add(resolverResult);
87 }
88 } catch (Throwable t) {
89 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving "+type.getSimpleName()+" "+t.getMessage());
90 }
91 return list;
92 }
93
94 private static <D extends Data> ResolverResult<D> resolveWithFallback(DNSName dnsName, Class<D> type) throws IOException {
95 try {
96 return DnssecResolverApi.INSTANCE.resolveDnssecReliable(dnsName, type);
97 } catch (DNSSECResultNotAuthenticException e) {
98 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving "+type.getSimpleName()+" with DNSSEC. Trying DNS instead.",e);
99 return ResolverApi.INSTANCE.resolve(dnsName, type);
100 } catch (IOException e) {
101 throw e;
102 } catch (Throwable throwable) {
103 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving "+type.getSimpleName()+" with DNSSEC. Trying DNS instead.",throwable);
104 return ResolverApi.INSTANCE.resolve(dnsName, type);
105 }
106 }
107
108 public static class Result implements Comparable<Result> {
109 private InetAddress ip;
110 private DNSName hostname;
111 private int port = 5222;
112 private boolean directTls = false;
113 private boolean authenticated =false;
114 private int priority;
115
116 public InetAddress getIp() {
117 return ip;
118 }
119
120 public int getPort() {
121 return port;
122 }
123
124 public DNSName getHostname() {
125 return hostname;
126 }
127
128 public boolean isDirectTls() {
129 return directTls;
130 }
131
132 public boolean isAuthenticated() {
133 return authenticated;
134 }
135
136 @Override
137 public String toString() {
138 return "Result{" +
139 "ip='" + (ip==null?null:ip.getHostAddress()) + '\'' +
140 ", hostame='" + hostname.toString() + '\'' +
141 ", port=" + port +
142 ", directTls=" + directTls +
143 ", authenticated=" + authenticated +
144 ", priority=" + priority +
145 '}';
146 }
147
148 @Override
149 public int compareTo(@NonNull Result result) {
150 if (result.priority == priority) {
151 if (directTls == result.directTls) {
152 if (ip == null && result.ip == null) {
153 return 0;
154 } else {
155 return ip != null ? -1 : 1;
156 }
157 } else {
158 return directTls ? -1 : 1;
159 }
160 } else {
161 return priority - result.priority;
162 }
163 }
164
165 public static Result fromRecord(SRV srv, boolean directTls) {
166 Result result = new Result();
167 result.port = srv.port;
168 result.hostname = srv.name;
169 result.directTls = directTls;
170 result.priority = srv.priority;
171 return result;
172 }
173
174 public static Result createDefault(String domain) {
175 Result result = new Result();
176 result.port = 5222;
177 result.hostname = DNSName.from(domain);
178 return result;
179 }
180 }
181
182}