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.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 final ResolverResult<D> r = DnssecResolverApi.INSTANCE.resolveDnssecReliable(dnsName, type);
98 if (r.wasSuccessful()) {
99 if (r.getAnswers().isEmpty() && type.equals(SRV.class)) {
100 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": resolving SRV records of "+dnsName.toString()+" with DNSSEC yielded empty result");
101 }
102 return r;
103 }
104 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving "+type.getSimpleName()+" with DNSSEC. Trying DNS instead.",r.getResolutionUnsuccessfulException());
105 } catch (DNSSECResultNotAuthenticException e) {
106 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving "+type.getSimpleName()+" with DNSSEC. Trying DNS instead.",e);
107 } catch (IOException e) {
108 throw e;
109 } catch (Throwable throwable) {
110 Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": error resolving "+type.getSimpleName()+" with DNSSEC. Trying DNS instead.",throwable);
111 }
112 return ResolverApi.INSTANCE.resolve(dnsName, type);
113 }
114
115 public static class Result implements Comparable<Result> {
116 private InetAddress ip;
117 private DNSName hostname;
118 private int port = 5222;
119 private boolean directTls = false;
120 private boolean authenticated =false;
121 private int priority;
122
123 public InetAddress getIp() {
124 return ip;
125 }
126
127 public int getPort() {
128 return port;
129 }
130
131 public DNSName getHostname() {
132 return hostname;
133 }
134
135 public boolean isDirectTls() {
136 return directTls;
137 }
138
139 public boolean isAuthenticated() {
140 return authenticated;
141 }
142
143 @Override
144 public String toString() {
145 return "Result{" +
146 "ip='" + (ip==null?null:ip.getHostAddress()) + '\'' +
147 ", hostame='" + hostname.toString() + '\'' +
148 ", port=" + port +
149 ", directTls=" + directTls +
150 ", authenticated=" + authenticated +
151 ", priority=" + priority +
152 '}';
153 }
154
155 @Override
156 public int compareTo(@NonNull Result result) {
157 if (result.priority == priority) {
158 if (directTls == result.directTls) {
159 if (ip == null && result.ip == null) {
160 return 0;
161 } else if (ip != null && result.ip != null) {
162 if (ip instanceof Inet4Address && result.ip instanceof Inet4Address) {
163 return 0;
164 } else {
165 return ip instanceof Inet4Address ? -1 : 1;
166 }
167 } else {
168 return ip != null ? -1 : 1;
169 }
170 } else {
171 return directTls ? -1 : 1;
172 }
173 } else {
174 return priority - result.priority;
175 }
176 }
177
178 public static Result fromRecord(SRV srv, boolean directTls) {
179 Result result = new Result();
180 result.port = srv.port;
181 result.hostname = srv.name;
182 result.directTls = directTls;
183 result.priority = srv.priority;
184 return result;
185 }
186
187 public static Result createDefault(String domain) {
188 Result result = new Result();
189 result.port = 5222;
190 result.hostname = DNSName.from(domain);
191 return result;
192 }
193 }
194
195}