| /* |
| * 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]; |
| } |
| }; |
| |
| } |