am 2df0f9ed: am 442a8753: am c3415a91: Merge "Remove ArpPeer; dead code from Google TV."

/*

 * Copyright (C) 2012 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package android.net.arp;

import android.net.LinkAddress;

import android.net.LinkProperties;

import android.net.RouteInfo;

import android.os.SystemClock;

import android.util.Log;

import java.io.IOException;

import java.net.InetAddress;

import java.net.Inet6Address;

import java.net.SocketException;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.util.Arrays;

import libcore.net.RawSocket;

/**

 * This class allows simple ARP exchanges over an uninitialized network

 * interface.

 *

 * @hide

 */

public class ArpPeer {

    private static final boolean DBG = false;

    private static final String TAG = "ArpPeer";

    private String mInterfaceName;

    private final InetAddress mMyAddr;

    private final byte[] mMyMac = new byte[6];

    private final InetAddress mPeer;

    private final RawSocket mSocket;

    private final byte[] L2_BROADCAST;  // TODO: refactor from DhcpClient.java

    private static final int MAX_LENGTH = 1500; // refactor from DhcpPacket.java

    private static final int ETHERNET_TYPE = 1;

    private static final int ARP_LENGTH = 28;

    private static final int MAC_ADDR_LENGTH = 6;

    private static final int IPV4_LENGTH = 4;

    public ArpPeer(String interfaceName, InetAddress myAddr, String mac,

                   InetAddress peer) throws SocketException {

        mInterfaceName = interfaceName;

        mMyAddr = myAddr;

        if (mac != null) {

            for (int i = 0; i < MAC_ADDR_LENGTH; i++) {

                mMyMac[i] = (byte) Integer.parseInt(mac.substring(

                            i*3, (i*3) + 2), 16);

            }

        }

        if (myAddr instanceof Inet6Address || peer instanceof Inet6Address) {

            throw new IllegalArgumentException("IPv6 unsupported");

        }

        mPeer = peer;

        L2_BROADCAST = new byte[MAC_ADDR_LENGTH];

        Arrays.fill(L2_BROADCAST, (byte) 0xFF);

        mSocket = new RawSocket(mInterfaceName, RawSocket.ETH_P_ARP);

    }

    /**

     * Returns the MAC address (or null if timeout) for the requested

     * peer.

     */

    public byte[] doArp(int timeoutMillis) {

        ByteBuffer buf = ByteBuffer.allocate(MAX_LENGTH);

        byte[] desiredIp = mPeer.getAddress();

        long timeout = SystemClock.elapsedRealtime() + timeoutMillis;

        // construct ARP request packet, using a ByteBuffer as a

        // convenient container

        buf.clear();

        buf.order(ByteOrder.BIG_ENDIAN);

        buf.putShort((short) ETHERNET_TYPE); // Ethernet type, 16 bits

        buf.putShort(RawSocket.ETH_P_IP); // Protocol type IP, 16 bits

        buf.put((byte)MAC_ADDR_LENGTH);  // MAC address length, 6 bytes

        buf.put((byte)IPV4_LENGTH);  // IPv4 protocol size

        buf.putShort((short) 1); // ARP opcode 1: 'request'

        buf.put(mMyMac);        // six bytes: sender MAC

        buf.put(mMyAddr.getAddress());  // four bytes: sender IP address

        buf.put(new byte[MAC_ADDR_LENGTH]); // target MAC address: unknown

        buf.put(desiredIp); // target IP address, 4 bytes

        buf.flip();

        mSocket.write(L2_BROADCAST, buf.array(), 0, buf.limit());

        byte[] recvBuf = new byte[MAX_LENGTH];

        while (SystemClock.elapsedRealtime() < timeout) {

            long duration = (long) timeout - SystemClock.elapsedRealtime();

            int readLen = mSocket.read(recvBuf, 0, recvBuf.length, -1,

                (int) duration);

            // Verify packet details. see RFC 826

            if ((readLen >= ARP_LENGTH) // trailing bytes at times

                && (recvBuf[0] == 0) && (recvBuf[1] == ETHERNET_TYPE) // type Ethernet

                && (recvBuf[2] == 8) && (recvBuf[3] == 0) // protocol IP

                && (recvBuf[4] == MAC_ADDR_LENGTH) // mac length

                && (recvBuf[5] == IPV4_LENGTH) // IPv4 protocol size

                && (recvBuf[6] == 0) && (recvBuf[7] == 2) // ARP reply

                // verify desired IP address

                && (recvBuf[14] == desiredIp[0]) && (recvBuf[15] == desiredIp[1])

                && (recvBuf[16] == desiredIp[2]) && (recvBuf[17] == desiredIp[3]))

            {

                // looks good.  copy out the MAC

                byte[] result = new byte[MAC_ADDR_LENGTH];

                System.arraycopy(recvBuf, 8, result, 0, MAC_ADDR_LENGTH);

                return result;

            }

        }

        return null;

    }

    public static boolean doArp(String myMacAddress, LinkProperties linkProperties,

            int timeoutMillis, int numArpPings, int minArpResponses) {

        String interfaceName = linkProperties.getInterfaceName();

        InetAddress inetAddress = null;

        InetAddress gateway = null;

        boolean success;

        for (LinkAddress la : linkProperties.getLinkAddresses()) {

            inetAddress = la.getAddress();

            break;

        }

        for (RouteInfo route : linkProperties.getRoutes()) {

            gateway = route.getGateway();

            break;

        }

        try {

            ArpPeer peer = new ArpPeer(interfaceName, inetAddress, myMacAddress, gateway);

            int responses = 0;

            for (int i=0; i < numArpPings; i++) {

                if(peer.doArp(timeoutMillis) != null) responses++;

            }

            if (DBG) Log.d(TAG, "ARP test result: " + responses + "/" + numArpPings);

            success = (responses >= minArpResponses);

            peer.close();

        } catch (SocketException se) {

            //Consider an Arp socket creation issue as a successful Arp

            //test to avoid any wifi connectivity issues

            Log.e(TAG, "ARP test initiation failure: " + se);

            success = true;

        }

        return success;

    }

    public void close() {

        try {

            mSocket.close();

        } catch (IOException ex) {

        }

    }

}