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