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authorDaniel Gultsch <daniel.gultsch@rwth-aachen.de>2014-02-07 06:52:09 +0100
committerDaniel Gultsch <daniel.gultsch@rwth-aachen.de>2014-02-07 06:52:09 +0100
commit86dbb2f411c28a5eaae207caf1e6bcd1e56503b0 (patch)
treec85031c36881c0fd92567f90c78571468b684301 /src/de/gultsch/chat/utils/DNSHelper.java
parentcda1c2c3a12b4c18f13771dd4b58aab6e465176b (diff)
wrote the scariest code ever to fetch srv records from dns. todo use real dns servers and dont hard code 8.8.8.8
Diffstat (limited to '')
-rw-r--r--src/de/gultsch/chat/utils/DNSHelper.java93
1 files changed, 93 insertions, 0 deletions
diff --git a/src/de/gultsch/chat/utils/DNSHelper.java b/src/de/gultsch/chat/utils/DNSHelper.java
new file mode 100644
index 00000000..f19b1b6f
--- /dev/null
+++ b/src/de/gultsch/chat/utils/DNSHelper.java
@@ -0,0 +1,93 @@
+package de.gultsch.chat.utils;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+import java.util.Random;
+
+import android.os.Bundle;
+import android.util.Log;
+
+public class DNSHelper {
+ public static Bundle getSRVRecord(String host) {
+ Bundle namePort = new Bundle();
+ try {
+ String[] hostParts = host.split("\\.");
+ byte[] transId = new byte[2];
+ Random random = new Random();
+ random.nextBytes(transId);
+ byte[] header = { 0x01, 0x20, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x01, 0x0c, 0x5f, 0x78, 0x6d, 0x70, 0x70, 0x2d, 0x63,
+ 0x6c, 0x69, 0x65, 0x6e, 0x74, 0x04, 0x5f, 0x74, 0x63, 0x70 };
+ byte[] rest = { 0x00, 0x00, 0x21, 0x00, 0x01, 0x00, 0x00, 0x29,
+ 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
+ ByteArrayOutputStream output = new ByteArrayOutputStream();
+ output.write(transId);
+ output.write(header);
+ for (int i = 0; i < hostParts.length; ++i) {
+ char[] tmpChars = hostParts[i].toCharArray();
+ byte[] tmp = new byte[tmpChars.length];
+ for (int j = 0; j < tmpChars.length; ++j) {
+ tmp[j] = (byte) tmpChars[j];
+ }
+ output.write(tmp.length);
+ output.write(tmp);
+ }
+ output.write(rest);
+ byte[] sendPaket = output.toByteArray();
+ byte[] addr = { 0x8, 0x8, 0x8, 0x8 };
+ int realLenght = sendPaket.length - 11;
+ DatagramPacket packet = new DatagramPacket(sendPaket,
+ sendPaket.length, InetAddress.getByAddress(addr), 53);
+ DatagramSocket datagramSocket = new DatagramSocket();
+ datagramSocket.send(packet);
+ byte[] receiveData = new byte[1024];
+
+ DatagramPacket receivePacket = new DatagramPacket(receiveData,
+ receiveData.length);
+ datagramSocket.setSoTimeout(2000);
+ datagramSocket.receive(receivePacket);
+ if (receiveData[3]!=-128) {
+ namePort.putString("error", "nosrv");
+ return namePort;
+ }
+ namePort.putInt("port",calcPort(receiveData[realLenght + 16],
+ receiveData[realLenght + 17]));
+ int i = realLenght + 18;
+ int wordLenght = 0;
+ StringBuilder builder = new StringBuilder();
+ while (receiveData[i] != 0) {
+ if (wordLenght > 0) {
+ builder.append((char) receiveData[i]);
+ --wordLenght;
+ } else {
+ wordLenght = receiveData[i];
+ builder.append(".");
+ }
+ ++i;
+ }
+ builder.replace(0, 1, "");
+ namePort.putString("name",builder.toString());
+ } catch (IOException e) {
+ Log.d("xmppService","gut" + e.getMessage());
+ }
+ return namePort;
+ }
+
+ static int calcPort(byte hb, byte lb) {
+ return ((int) hb << 8) | ((int) lb & 0xFF);
+ }
+
+ final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
+ public static String bytesToHex(byte[] bytes) {
+ char[] hexChars = new char[bytes.length * 2];
+ for ( int j = 0; j < bytes.length; j++ ) {
+ int v = bytes[j] & 0xFF;
+ hexChars[j * 2] = hexArray[v >>> 4];
+ hexChars[j * 2 + 1] = hexArray[v & 0x0F];
+ }
+ return new String(hexChars);
+ }
+}