1package eu.siacs.conversations.utils;
2
3import de.measite.minidns.Client;
4import de.measite.minidns.DNSMessage;
5import de.measite.minidns.Record;
6import de.measite.minidns.Record.TYPE;
7import de.measite.minidns.Record.CLASS;
8import de.measite.minidns.record.SRV;
9import de.measite.minidns.record.A;
10import de.measite.minidns.record.AAAA;
11import de.measite.minidns.record.Data;
12import de.measite.minidns.util.NameUtil;
13import eu.siacs.conversations.Config;
14import eu.siacs.conversations.xmpp.jid.Jid;
15
16import java.io.IOException;
17import java.net.InetAddress;
18import java.net.SocketTimeoutException;
19import java.util.ArrayList;
20import java.util.Collections;
21import java.util.Random;
22import java.util.TreeMap;
23
24import android.os.Bundle;
25import android.util.Log;
26
27public class DNSHelper {
28 protected static Client client = new Client();
29
30 public static Bundle getSRVRecord(final Jid jid) throws IOException {
31 final String host = jid.getDomainpart();
32 String dns[] = client.findDNS();
33
34 if (dns != null) {
35 for (String dnsserver : dns) {
36 InetAddress ip = InetAddress.getByName(dnsserver);
37 Bundle b = queryDNS(host, ip);
38 if (b.containsKey("values")) {
39 return b;
40 }
41 }
42 }
43 return queryDNS(host, InetAddress.getByName("8.8.8.8"));
44 }
45
46 public static Bundle queryDNS(String host, InetAddress dnsServer) {
47 Bundle bundle = new Bundle();
48 try {
49 String qname = "_xmpp-client._tcp." + host;
50 Log.d(Config.LOGTAG,
51 "using dns server: " + dnsServer.getHostAddress()
52 + " to look up " + host);
53 DNSMessage message = client.query(qname, TYPE.SRV, CLASS.IN,
54 dnsServer.getHostAddress());
55
56 // How should we handle priorities and weight?
57 // Wikipedia has a nice article about priorities vs. weights:
58 // https://en.wikipedia.org/wiki/SRV_record#Provisioning_for_high_service_availability
59
60 // we bucket the SRV records based on priority, pick per priority
61 // a random order respecting the weight, and dump that priority by
62 // priority
63
64 TreeMap<Integer, ArrayList<SRV>> priorities = new TreeMap<>();
65 TreeMap<String, ArrayList<String>> ips4 = new TreeMap<>();
66 TreeMap<String, ArrayList<String>> ips6 = new TreeMap<>();
67
68 for (Record[] rrset : new Record[][] { message.getAnswers(),
69 message.getAdditionalResourceRecords() }) {
70 for (Record rr : rrset) {
71 Data d = rr.getPayload();
72 if (d instanceof SRV
73 && NameUtil.idnEquals(qname, rr.getName())) {
74 SRV srv = (SRV) d;
75 if (!priorities.containsKey(srv.getPriority())) {
76 priorities.put(srv.getPriority(),
77 new ArrayList<SRV>(2));
78 }
79 priorities.get(srv.getPriority()).add(srv);
80 }
81 if (d instanceof A) {
82 A arecord = (A) d;
83 if (!ips4.containsKey(rr.getName())) {
84 ips4.put(rr.getName(), new ArrayList<String>(3));
85 }
86 ips4.get(rr.getName()).add(arecord.toString());
87 }
88 if (d instanceof AAAA) {
89 AAAA aaaa = (AAAA) d;
90 if (!ips6.containsKey(rr.getName())) {
91 ips6.put(rr.getName(), new ArrayList<String>(3));
92 }
93 ips6.get(rr.getName()).add("[" + aaaa.toString() + "]");
94 }
95 }
96 }
97
98 Random rnd = new Random();
99 ArrayList<SRV> result = new ArrayList<>(
100 priorities.size() * 2 + 1);
101 for (ArrayList<SRV> s : priorities.values()) {
102
103 // trivial case
104 if (s.size() <= 1) {
105 result.addAll(s);
106 continue;
107 }
108
109 long totalweight = 0l;
110 for (SRV srv : s) {
111 totalweight += srv.getWeight();
112 }
113
114 while (totalweight > 0l && s.size() > 0) {
115 long p = (rnd.nextLong() & 0x7fffffffffffffffl)
116 % totalweight;
117 int i = 0;
118 while (p > 0) {
119 p -= s.get(i++).getPriority();
120 }
121 if (i>0) i--;
122 // remove is expensive, but we have only a few entries
123 // anyway
124 SRV srv = s.remove(i);
125 totalweight -= srv.getWeight();
126 result.add(srv);
127 }
128
129 Collections.shuffle(s, rnd);
130 result.addAll(s);
131
132 }
133
134 ArrayList<Bundle> values = new ArrayList<>();
135 if (result.size() == 0) {
136 DNSMessage response;
137 response = client.query(host, TYPE.A, CLASS.IN, dnsServer.getHostAddress());
138 for(int i = 0; i < response.getAnswers().length; ++i) {
139 values.add(createNamePortBundle(host,5222,response.getAnswers()[i].getPayload()));
140 }
141 response = client.query(host, TYPE.AAAA, CLASS.IN, dnsServer.getHostAddress());
142 for(int i = 0; i < response.getAnswers().length; ++i) {
143 values.add(createNamePortBundle(host,5222,response.getAnswers()[i].getPayload()));
144 }
145 bundle.putParcelableArrayList("values", values);
146 return bundle;
147 }
148 for (SRV srv : result) {
149 if (ips6.containsKey(srv.getName())) {
150 values.add(createNamePortBundle(srv.getName(),srv.getPort(),ips6));
151 } else {
152 DNSMessage response = client.query(srv.getName(), TYPE.AAAA, CLASS.IN, dnsServer.getHostAddress());
153 for(int i = 0; i < response.getAnswers().length; ++i) {
154 values.add(createNamePortBundle(host,5222,response.getAnswers()[i].getPayload()));
155 }
156 }
157 if (ips4.containsKey(srv.getName())) {
158 values.add(createNamePortBundle(srv.getName(),srv.getPort(),ips4));
159 } else {
160 DNSMessage response = client.query(srv.getName(), TYPE.A, CLASS.IN, dnsServer.getHostAddress());
161 for(int i = 0; i < response.getAnswers().length; ++i) {
162 values.add(createNamePortBundle(host,5222,response.getAnswers()[i].getPayload()));
163 }
164 }
165 values.add(createNamePortBundle(srv.getName(), srv.getPort()));
166 }
167 bundle.putParcelableArrayList("values", values);
168 } catch (SocketTimeoutException e) {
169 bundle.putString("error", "timeout");
170 } catch (Exception e) {
171 Log.d(Config.LOGTAG,e.getMessage());
172 bundle.putString("error", "unhandled");
173 }
174 return bundle;
175 }
176
177 private static Bundle createNamePortBundle(String name, int port) {
178 Bundle namePort = new Bundle();
179 namePort.putString("name", name);
180 namePort.putInt("port", port);
181 return namePort;
182 }
183
184 private static Bundle createNamePortBundle(String name, int port, TreeMap<String, ArrayList<String>> ips) {
185 Bundle namePort = new Bundle();
186 namePort.putString("name", name);
187 namePort.putInt("port", port);
188 if (ips!=null) {
189 ArrayList<String> ip = ips.get(name);
190 Collections.shuffle(ip, new Random());
191 namePort.putString("ip", ip.get(0));
192 }
193 return namePort;
194 }
195
196 private static Bundle createNamePortBundle(String name, int port, Data data) {
197 Bundle namePort = new Bundle();
198 namePort.putString("name", name);
199 namePort.putInt("port", port);
200 if (data instanceof A) {
201 namePort.putString("ip", data.toString());
202 } else if (data instanceof AAAA) {
203 namePort.putString("ip","["+data.toString()+"]");
204 }
205 return namePort;
206 }
207
208 final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
209
210 public static String bytesToHex(byte[] bytes) {
211 char[] hexChars = new char[bytes.length * 2];
212 for (int j = 0; j < bytes.length; j++) {
213 int v = bytes[j] & 0xFF;
214 hexChars[j * 2] = hexArray[v >>> 4];
215 hexChars[j * 2 + 1] = hexArray[v & 0x0F];
216 }
217 return new String(hexChars);
218 }
219}