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Try various ways to get the dns settings

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This commit is contained in:
Rene Treffer 2014-04-02 22:45:57 +02:00
parent 32b27c53e0
commit d5cca3b3a4
1 changed files with 90 additions and 1 deletions
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91
src/de/measite/minidns/Client.java
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@ -4,14 +4,18 @@ import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.lang.reflect.Method;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Random;
import android.util.Log;
import de.measite.minidns.Record.CLASS;
import de.measite.minidns.Record.TYPE;
@ -130,6 +134,33 @@ public class Client {
* @return The server array.
*/
public String[] findDNS() {
String[] result = findDNSByReflection();
if (result != null) {
Log.d("minidns/client",
"Got DNS servers via reflection: " + Arrays.toString(result));
return result;
}
result = findDNSByExec();
if (result != null) {
Log.d("minidns/client",
"Got DNS servers via exec: " + Arrays.toString(result));
return result;
}
// fallback for ipv4 and ipv6 connectivity
// see https://developers.google.com/speed/public-dns/docs/using
Log.d("minidns/client",
"No DNS found? Using fallback [8.8.8.8, [2001:4860:4860::8888]]");
return new String[]{"8.8.8.8", "[2001:4860:4860::8888]"};
}
/**
* Try to retrieve the list of dns server by executing getprop.
* @return Array of servers, or null on failure.
*/
protected String[] findDNSByExec() {
try {
Process process = Runtime.getRuntime().exec("getprop");
InputStream inputStream = process.getInputStream();
@ -146,7 +177,19 @@ public class Client {
String value = line.substring(split + 4, line.length() - 1);
if (property.endsWith(".dns") || property.endsWith(".dns1") ||
property.endsWith(".dns2") || property.endsWith(".dns3") ||
property.endsWith(".dns4")) {
property.endsWith(".dns4")) {
// normalize the address
InetAddress ip = InetAddress.getByName(value);
if (ip == null) continue;
value = ip.getHostAddress();
if (value == null) continue;
if (value.length() == 0) continue;
server.add(value);
}
}
@ -158,4 +201,50 @@ public class Client {
}
return null;
}
/**
* Try to retrieve the list of dns server by calling SystemProperties.
* @return Array of servers, or null on failure.
*/
protected String[] findDNSByReflection() {
try {
Class<?> SystemProperties =
Class.forName("android.os.SystemProperties");
Method method = SystemProperties.getMethod("get",
new Class[] { String.class });
ArrayList<String> servers = new ArrayList<String>(5);
for (String propKey : new String[] {
"net.dns1", "net.dns2", "net.dns3", "net.dns4"}) {
String value = (String)method.invoke(null, propKey);
if (value == null) continue;
if (value.length() == 0) continue;
if (servers.contains(value)) continue;
InetAddress ip = InetAddress.getByName(value);
if (ip == null) continue;
value = ip.getHostAddress();
if (value == null) continue;
if (value.length() == 0) continue;
if (servers.contains(value)) continue;
servers.add(value);
}
if (servers.size() > 0) {
return servers.toArray(new String[servers.size()]);
}
} catch (Exception e) {
// we might trigger some problems this way
e.printStackTrace();
}
return null;
}
}