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/*
* Copyright (C) 2015 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;
import android.system.OsConstants;
import android.net.ConnectivityManager;
import android.net.util.IpUtils;
import android.os.Parcel;
import android.os.Parcelable;
import android.system.OsConstants;
import android.util.Log;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import static android.net.ConnectivityManager.PacketKeepalive.*;
/**
* Represents the actual packets that are sent by the
* {@link android.net.ConnectivityManager.PacketKeepalive} API.
*
* @hide
*/
public class KeepalivePacketData implements Parcelable {
private static final String TAG = "KeepalivePacketData";
/** Source IP address */
public final InetAddress srcAddress;
/** Destination IP address */
public final InetAddress dstAddress;
/** Source port */
public final int srcPort;
/** Destination port */
public final int dstPort;
/** Packet data. A raw byte string of packet data, not including the link-layer header. */
private final byte[] mPacket;
private static final int IPV4_HEADER_LENGTH = 20;
private static final int UDP_HEADER_LENGTH = 8;
// This should only be constructed via static factory methods, such as
// nattKeepalivePacket
protected KeepalivePacketData(InetAddress srcAddress, int srcPort,
InetAddress dstAddress, int dstPort, byte[] data) throws InvalidPacketException {
this.srcAddress = srcAddress;
this.dstAddress = dstAddress;
this.srcPort = srcPort;
this.dstPort = dstPort;
this.mPacket = data;
// Check we have two IP addresses of the same family.
if (srcAddress == null || dstAddress == null || !srcAddress.getClass().getName()
.equals(dstAddress.getClass().getName())) {
Log.e(TAG, "Invalid or mismatched InetAddresses in KeepalivePacketData");
throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
}
// Check the ports.
if (!IpUtils.isValidUdpOrTcpPort(srcPort) || !IpUtils.isValidUdpOrTcpPort(dstPort)) {
Log.e(TAG, "Invalid ports in KeepalivePacketData");
throw new InvalidPacketException(ERROR_INVALID_PORT);
}
}
public static class InvalidPacketException extends Exception {
public final int error;
public InvalidPacketException(int error) {
this.error = error;
}
}
public byte[] getPacket() {
return mPacket.clone();
}
public static KeepalivePacketData nattKeepalivePacket(
InetAddress srcAddress, int srcPort, InetAddress dstAddress, int dstPort)
throws InvalidPacketException {
// FIXME: remove this and actually support IPv6 keepalives
if (srcAddress instanceof Inet6Address && dstAddress instanceof Inet6Address) {
// Optimistically returning an IPv6 Keepalive Packet with no data,
// which currently only works on cellular
return new KeepalivePacketData(srcAddress, srcPort, dstAddress, dstPort, new byte[0]);
}
if (!(srcAddress instanceof Inet4Address) || !(dstAddress instanceof Inet4Address)) {
throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
}
if (dstPort != NATT_PORT) {
throw new InvalidPacketException(ERROR_INVALID_PORT);
}
int length = IPV4_HEADER_LENGTH + UDP_HEADER_LENGTH + 1;
ByteBuffer buf = ByteBuffer.allocate(length);
buf.order(ByteOrder.BIG_ENDIAN);
buf.putShort((short) 0x4500); // IP version and TOS
buf.putShort((short) length);
buf.putInt(0); // ID, flags, offset
buf.put((byte) 64); // TTL
buf.put((byte) OsConstants.IPPROTO_UDP);
int ipChecksumOffset = buf.position();
buf.putShort((short) 0); // IP checksum
buf.put(srcAddress.getAddress());
buf.put(dstAddress.getAddress());
buf.putShort((short) srcPort);
buf.putShort((short) dstPort);
buf.putShort((short) (length - 20)); // UDP length
int udpChecksumOffset = buf.position();
buf.putShort((short) 0); // UDP checksum
buf.put((byte) 0xff); // NAT-T keepalive
buf.putShort(ipChecksumOffset, IpUtils.ipChecksum(buf, 0));
buf.putShort(udpChecksumOffset, IpUtils.udpChecksum(buf, 0, IPV4_HEADER_LENGTH));
return new KeepalivePacketData(srcAddress, srcPort, dstAddress, dstPort, buf.array());
}
/* Parcelable Implementation */
public int describeContents() {
return 0;
}
/** Write to parcel */
public void writeToParcel(Parcel out, int flags) {
out.writeString(srcAddress.getHostAddress());
out.writeString(dstAddress.getHostAddress());
out.writeInt(srcPort);
out.writeInt(dstPort);
out.writeByteArray(mPacket);
}
private KeepalivePacketData(Parcel in) {
srcAddress = NetworkUtils.numericToInetAddress(in.readString());
dstAddress = NetworkUtils.numericToInetAddress(in.readString());
srcPort = in.readInt();
dstPort = in.readInt();
mPacket = in.createByteArray();
}
/** Parcelable Creator */
public static final Parcelable.Creator<KeepalivePacketData> CREATOR =
new Parcelable.Creator<KeepalivePacketData>() {
public KeepalivePacketData createFromParcel(Parcel in) {
return new KeepalivePacketData(in);
}
public KeepalivePacketData[] newArray(int size) {
return new KeepalivePacketData[size];
}
};
}
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