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Commit 0f27eed8 authored by Erik Kline's avatar Erik Kline
Browse files

Randomize the local Wifi IPv4 address 

Also: address a few "error prone" warnings, adding @Override where missing

Test: as follows
    - built, flashed, booted
    - runtest frameworks-net passes (with --no-hidden-api-checks)
    - wifi tethering uses a randomized address, in as much as it can work
Bug: 32163131
Bug: 70673901

Change-Id: Icfabc48f2cf97b362ce292747f47021e84b900da
parent 4d3b5c1d

services/core/java/com/android/server/connectivity/tethering/OffloadController.java

+1 −0
Original line number Diff line number Diff line
@@ -282,6 +282,7 @@ public class OffloadController { 
            return stats;

        }



        @Override

        public void setInterfaceQuota(String iface, long quotaBytes) {

            mHandler.post(() -> {

                if (quotaBytes == ITetheringStatsProvider.QUOTA_UNLIMITED) {

services/core/java/com/android/server/connectivity/tethering/OffloadHardwareInterface.java

+1 −0
Original line number Diff line number Diff line
@@ -355,6 +355,7 @@ public class OffloadHardwareInterface { 
        boolean success;

        String errMsg;



        @Override

        public String toString() {

            if (success) {

                return "ok";

services/core/java/com/android/server/connectivity/tethering/TetherInterfaceStateMachine.java

+20 −6
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ 


package com.android.server.connectivity.tethering;



import static android.net.util.NetworkConstants.asByte;

import static android.net.util.NetworkConstants.FF;

import static android.net.util.NetworkConstants.RFC7421_PREFIX_LENGTH;



import android.net.ConnectivityManager;
@@ -64,6 +66,7 @@ import java.util.Set; 
 */

public class TetherInterfaceStateMachine extends StateMachine {

    private static final IpPrefix LINK_LOCAL_PREFIX = new IpPrefix("fe80::/64");

    private static final byte DOUG_ADAMS = (byte) 42;



    private static final String USB_NEAR_IFACE_ADDR = "192.168.42.129";

    private static final int USB_PREFIX_LENGTH = 24;
@@ -204,7 +207,7 @@ public class TetherInterfaceStateMachine extends StateMachine { 
            ipAsString = USB_NEAR_IFACE_ADDR;

            prefixLen = USB_PREFIX_LENGTH;

        } else if (mInterfaceType == ConnectivityManager.TETHERING_WIFI) {

            ipAsString = WIFI_HOST_IFACE_ADDR;

            ipAsString = getRandomWifiIPv4Address();

            prefixLen = WIFI_HOST_IFACE_PREFIX_LENGTH;

        } else {

            // Nothing to do, BT does this elsewhere.
@@ -253,6 +256,16 @@ public class TetherInterfaceStateMachine extends StateMachine { 
        return true;

    }



    private String getRandomWifiIPv4Address() {

        try {

            byte[] bytes = NetworkUtils.numericToInetAddress(WIFI_HOST_IFACE_ADDR).getAddress();

            bytes[3] = getRandomSanitizedByte(DOUG_ADAMS, asByte(0), asByte(1), FF);

            return InetAddress.getByAddress(bytes).getHostAddress();

        } catch (Exception e) {

            return WIFI_HOST_IFACE_ADDR;

        }

    }



    private boolean startIPv6() {

        mInterfaceParams = mDeps.getInterfaceParams(mIfaceName);

        if (mInterfaceParams == null) {
@@ -757,7 +770,7 @@ public class TetherInterfaceStateMachine extends StateMachine { 
    // Given a prefix like 2001:db8::/64 return an address like 2001:db8::1.

    private static Inet6Address getLocalDnsIpFor(IpPrefix localPrefix) {

        final byte[] dnsBytes = localPrefix.getRawAddress();

        dnsBytes[dnsBytes.length - 1] = getRandomNonZeroByte();

        dnsBytes[dnsBytes.length - 1] = getRandomSanitizedByte(DOUG_ADAMS, asByte(0), asByte(1));

        try {

            return Inet6Address.getByAddress(null, dnsBytes, 0);

        } catch (UnknownHostException e) {
@@ -766,10 +779,11 @@ public class TetherInterfaceStateMachine extends StateMachine { 
        }

    }



    private static byte getRandomNonZeroByte() {

    private static byte getRandomSanitizedByte(byte dflt, byte... excluded) {

        final byte random = (byte) (new Random()).nextInt();

        // Don't pick the subnet-router anycast address, since that might be

        // in use on the upstream already.

        return (random != 0) ? random : 0x1;

        for (int value : excluded) {

            if (random == value) return dflt;

        }

        return random;

    }

}

services/net/java/android/net/util/NetworkConstants.java

+1 −1
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ public final class NetworkConstants { 


    public static final int ETHER_HEADER_LEN = 14;



    private static final byte FF = asByte(0xff);

    public static final byte FF = asByte(0xff);

    public static final byte[] ETHER_ADDR_BROADCAST = {

        FF, FF, FF, FF, FF, FF

    };