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Commit 3ee9d05d authored by Isaac Levy's avatar Isaac Levy
Browse files

DnsPinger changes incl. binding 

- Now attempting to bind the socket
- Now pinging google.com rather than android.com

Change-Id: I7fb6522ef66068a6e2faca43d3af12c9f1d0585b
parent e2474bc7

services/java/com/android/server/DnsPinger.java

+44 −34
Original line number Diff line number Diff line
@@ -16,7 +16,6 @@ 


package com.android.server;



import android.content.ContentResolver;

import android.content.Context;

import android.net.ConnectivityManager;

import android.net.LinkProperties;
@@ -28,6 +27,7 @@ import android.util.Slog; 
import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.NetworkInterface;

import java.net.SocketTimeoutException;

import java.util.Collection;

import java.util.Random;
@@ -49,7 +49,7 @@ public final class DnsPinger { 
    private static final boolean V = true;



    /** Number of bytes for the query */

    private static final int DNS_QUERY_BASE_SIZE = 33;

    private static final int DNS_QUERY_BASE_SIZE = 32;



    /** The DNS port */

    private static final int DNS_PORT = 53;
@@ -84,12 +84,7 @@ public final class DnsPinger { 
     *         dns set. Should not be null.

     */

    public InetAddress getDns() {

        if (mConnectivityManager == null) {

            mConnectivityManager = (ConnectivityManager) mContext.getSystemService(

                    Context.CONNECTIVITY_SERVICE);

        }



        LinkProperties curLinkProps = mConnectivityManager.getLinkProperties(mConnectionType);

        LinkProperties curLinkProps = getCurrentLinkProperties();

        if (curLinkProps == null) {

            Slog.e(TAG, "getCurLinkProperties:: LP for type" + mConnectionType + " is null!");

            return mDefaultDns;
@@ -104,6 +99,15 @@ public final class DnsPinger { 
        return dnses.iterator().next();

    }



    private LinkProperties getCurrentLinkProperties() {

        if (mConnectivityManager == null) {

            mConnectivityManager = (ConnectivityManager) mContext.getSystemService(

                    Context.CONNECTIVITY_SERVICE);

        }



        return mConnectivityManager.getLinkProperties(mConnectionType);

    }



    private InetAddress getDefaultDns() {

        String dns = Settings.Secure.getString(mContext.getContentResolver(),

                Settings.Secure.DEFAULT_DNS_SERVER);
@@ -130,8 +134,15 @@ public final class DnsPinger { 
            // Set some socket properties

            socket.setSoTimeout(timeout);



            byte[] buf = new byte[DNS_QUERY_BASE_SIZE];

            fillQuery(buf);

            // Try to bind but continue ping if bind fails

            try {

                socket.setNetworkInterface(NetworkInterface.getByName(

                        getCurrentLinkProperties().getInterfaceName()));

            } catch (Exception e) {

                Slog.d(TAG,"pingDns::Error binding to socket", e);

            }



            byte[] buf = constructQuery();



            // Send the DNS query
@@ -164,48 +175,47 @@ public final class DnsPinger { 


    }



    private static void fillQuery(byte[] buf) {



        /*

         * See RFC2929 (though the bit tables in there are misleading for us.

         * For example, the recursion desired bit is the 0th bit for us, but

         * looking there it would appear as the 7th bit of the byte

    /**

     * @return google.com DNS query packet

     */



        // Make sure it's all zeroed out

        for (int i = 0; i < buf.length; i++)

            buf[i] = 0;



        // Form a query for www.android.com

    private static byte[] constructQuery() {

        byte[] buf = new byte[DNS_QUERY_BASE_SIZE];



        // [0-1] bytes are an ID, generate random ID for this query

        buf[0] = (byte) sRandom.nextInt(256);

        buf[1] = (byte) sRandom.nextInt(256);



        // [2-3] bytes are for flags.

        buf[2] = 1; // Recursion desired

        buf[2] = 0x01; // Recursion desired



        // [4-5] bytes are for the query count

        buf[5] = 1; // One query

        // [4-5] bytes are for number of queries (QCOUNT)

        buf[5] = 0x01;



        // [6-7] [8-9] [10-11] are all counts of other fields we don't use



        // [12-15] for www

        writeString(buf, 12, "www");



        // [16-23] for android

        writeString(buf, 16, "android");

        // [16-22] for google

        writeString(buf, 16, "google");



        // [23-26] for com

        writeString(buf, 23, "com");



        // [24-27] for com

        writeString(buf, 24, "com");

        // [27] is a null byte terminator byte for the url



        // [29-30] bytes are for QTYPE, set to 1

        buf[30] = 1;

        // [28-29] bytes are for QTYPE, set to 1 = A (host address)

        buf[29] = 0x01;



        // [31-32] bytes are for QCLASS, set to 1

        buf[32] = 1;

        // [30-31] bytes are for QCLASS, set to 1 = IN (internet)

        buf[31] = 0x01;



        return buf;

    }



    /**

     * Writes the string's length and its contents to the buffer

     */

    private static void writeString(byte[] buf, int startPos, String string) {

        int pos = startPos;