1package eu.siacs.conversations.utils;
2
3import java.io.ByteArrayOutputStream;
4import java.io.IOException;
5import java.lang.reflect.InvocationTargetException;
6import java.lang.reflect.Method;
7import java.net.DatagramPacket;
8import java.net.DatagramSocket;
9import java.net.InetAddress;
10import java.util.ArrayList;
11import java.util.Random;
12
13import android.os.Bundle;
14import android.util.Log;
15
16public class DNSHelper {
17 public static Bundle getSRVRecord(String host) throws IOException {
18 InetAddress ip = InetAddress.getByName("8.8.8.8");
19 try {
20 Class<?> SystemProperties = Class.forName("android.os.SystemProperties");
21 Method method = SystemProperties.getMethod("get", new Class[] { String.class });
22 ArrayList<String> servers = new ArrayList<String>();
23 for (String name : new String[] { "net.dns1", "net.dns2", "net.dns3", "net.dns4", }) {
24 String value = (String) method.invoke(null, name);
25
26 if (value != null && !"".equals(value) && !servers.contains(value))
27 ip = InetAddress.getByName(value);
28 servers.add(value);
29 Bundle result = queryDNS(host, ip);
30 if (!result.containsKey("error")) {
31 return result;
32 }
33 }
34 } catch (ClassNotFoundException e) {
35 ip = InetAddress.getByName("8.8.8.8");
36 } catch (NoSuchMethodException e) {
37 ip = InetAddress.getByName("8.8.8.8");
38 } catch (IllegalAccessException e) {
39 ip = InetAddress.getByName("8.8.8.8");
40 } catch (IllegalArgumentException e) {
41 ip = InetAddress.getByName("8.8.8.8");
42 } catch (InvocationTargetException e) {
43 ip = InetAddress.getByName("8.8.8.8");
44 }
45 return queryDNS(host, ip);
46 }
47
48 public static Bundle queryDNS(String host, InetAddress dnsServer) {
49 Bundle namePort = new Bundle();
50 try {
51 Log.d("xmppService","using dns server: "+dnsServer.toString()+" to look up "+host);
52 String[] hostParts = host.split("\\.");
53 byte[] transId = new byte[2];
54 Random random = new Random();
55 random.nextBytes(transId);
56 byte[] header = { 0x01, 0x20, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00,
57 0x00, 0x01, 0x0c, 0x5f, 0x78, 0x6d, 0x70, 0x70, 0x2d, 0x63,
58 0x6c, 0x69, 0x65, 0x6e, 0x74, 0x04, 0x5f, 0x74, 0x63, 0x70 };
59 byte[] rest = { 0x00, 0x00, 0x21, 0x00, 0x01, 0x00, 0x00, 0x29,
60 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
61 ByteArrayOutputStream output = new ByteArrayOutputStream();
62 output.write(transId);
63 output.write(header);
64 for (int i = 0; i < hostParts.length; ++i) {
65 char[] tmpChars = hostParts[i].toCharArray();
66 byte[] tmp = new byte[tmpChars.length];
67 for (int j = 0; j < tmpChars.length; ++j) {
68 tmp[j] = (byte) tmpChars[j];
69 }
70 output.write(tmp.length);
71 output.write(tmp);
72 }
73 output.write(rest);
74 byte[] sendPaket = output.toByteArray();
75 int realLenght = sendPaket.length - 11;
76 DatagramPacket packet = new DatagramPacket(sendPaket,
77 sendPaket.length, dnsServer, 53);
78 DatagramSocket datagramSocket = new DatagramSocket();
79 datagramSocket.send(packet);
80 byte[] receiveData = new byte[1024];
81
82 DatagramPacket receivePacket = new DatagramPacket(receiveData,
83 receiveData.length);
84 datagramSocket.setSoTimeout(3000);
85 datagramSocket.receive(receivePacket);
86 if (receiveData[3]!=-128) {
87 namePort.putString("error", "nosrv");
88 return namePort;
89 }
90 namePort.putInt("port",calcPort(receiveData[realLenght + 16],
91 receiveData[realLenght + 17]));
92 int i = realLenght + 18;
93 int wordLenght = 0;
94 StringBuilder builder = new StringBuilder();
95 while (receiveData[i] != 0) {
96 if (wordLenght > 0) {
97 builder.append((char) receiveData[i]);
98 --wordLenght;
99 } else {
100 wordLenght = receiveData[i];
101 builder.append(".");
102 }
103 ++i;
104 }
105 builder.replace(0, 1, "");
106 byte type = receiveData[i+1];
107 if (type!=-64) {
108 namePort.putString("error", "nosrv");
109 return namePort;
110 }
111 namePort.putString("name",builder.toString());
112 return namePort;
113 } catch (IOException e) {
114 Log.d("xmppService","io execpiton during dns");
115 namePort.putString("error", "nosrv");
116 return namePort;
117 }
118 }
119
120 static int calcPort(byte hb, byte lb) {
121 int port = ((int) hb << 8) | ((int) lb & 0xFF);
122 if (port>=0) {
123 return port;
124 } else {
125 return 65536 + port;
126 }
127 }
128
129 final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
130 public static String bytesToHex(byte[] bytes) {
131 char[] hexChars = new char[bytes.length * 2];
132 for ( int j = 0; j < bytes.length; j++ ) {
133 int v = bytes[j] & 0xFF;
134 hexChars[j * 2] = hexArray[v >>> 4];
135 hexChars[j * 2 + 1] = hexArray[v & 0x0F];
136 }
137 return new String(hexChars);
138 }
139}