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/*
* Copyright (C) 2016 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.ip;
import static android.system.OsConstants.*;
import android.net.NetworkUtils;
import android.net.util.BlockingSocketReader;
import android.net.util.ConnectivityPacketSummary;
import android.os.Handler;
import android.system.ErrnoException;
import android.system.Os;
import android.system.PacketSocketAddress;
import android.util.Log;
import android.util.LocalLog;
import libcore.io.IoBridge;
import libcore.util.HexEncoding;
import java.io.FileDescriptor;
import java.io.InterruptedIOException;
import java.io.IOException;
import java.net.NetworkInterface;
import java.net.SocketException;
/**
* Critical connectivity packet tracking daemon.
*
* Tracks ARP, DHCPv4, and IPv6 RS/RA/NS/NA packets.
*
* This class's constructor, start() and stop() methods must only be called
* from the same thread on which the passed in |log| is accessed.
*
* Log lines include a hexdump of the packet, which can be decoded via:
*
* echo -n H3XSTR1NG | sed -e 's/\([0-9A-F][0-9A-F]\)/\1 /g' -e 's/^/000000 /'
* | text2pcap - -
* | tcpdump -n -vv -e -r -
*
* @hide
*/
public class ConnectivityPacketTracker {
private static final String TAG = ConnectivityPacketTracker.class.getSimpleName();
private static final boolean DBG = false;
private static final String MARK_START = "--- START ---";
private static final String MARK_STOP = "--- STOP ---";
private final String mTag;
private final LocalLog mLog;
private final BlockingSocketReader mPacketListener;
private boolean mRunning;
public ConnectivityPacketTracker(Handler h, NetworkInterface netif, LocalLog log) {
final String ifname;
final int ifindex;
final byte[] hwaddr;
final int mtu;
try {
ifname = netif.getName();
ifindex = netif.getIndex();
hwaddr = netif.getHardwareAddress();
mtu = netif.getMTU();
} catch (NullPointerException|SocketException e) {
throw new IllegalArgumentException("bad network interface", e);
}
mTag = TAG + "." + ifname;
mLog = log;
mPacketListener = new PacketListener(h, ifindex, hwaddr, mtu);
}
public void start() {
mRunning = true;
mPacketListener.start();
}
public void stop() {
mPacketListener.stop();
mRunning = false;
}
private final class PacketListener extends BlockingSocketReader {
private final int mIfIndex;
private final byte mHwAddr[];
PacketListener(Handler h, int ifindex, byte[] hwaddr, int mtu) {
super(h, mtu);
mIfIndex = ifindex;
mHwAddr = hwaddr;
}
@Override
protected FileDescriptor createFd() {
FileDescriptor s = null;
try {
s = Os.socket(AF_PACKET, SOCK_RAW, 0);
NetworkUtils.attachControlPacketFilter(s, ARPHRD_ETHER);
Os.bind(s, new PacketSocketAddress((short) ETH_P_ALL, mIfIndex));
} catch (ErrnoException | IOException e) {
logError("Failed to create packet tracking socket: ", e);
closeFd(s);
return null;
}
return s;
}
@Override
protected void handlePacket(byte[] recvbuf, int length) {
final String summary = ConnectivityPacketSummary.summarize(
mHwAddr, recvbuf, length);
if (summary == null) return;
if (DBG) Log.d(mTag, summary);
addLogEntry(summary +
"\n[" + new String(HexEncoding.encode(recvbuf, 0, length)) + "]");
}
@Override
protected void onStart() {
mLog.log(MARK_START);
}
@Override
protected void onStop() {
if (mRunning) {
mLog.log(MARK_STOP);
} else {
mLog.log(MARK_STOP + " (packet listener stopped unexpectedly)");
}
}
@Override
protected void logError(String msg, Exception e) {
Log.e(mTag, msg, e);
addLogEntry(msg + e);
}
private void addLogEntry(String entry) {
mLog.log(entry);
}
}
}
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