| /* |
| * 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 com.android.server.connectivity; |
| |
| import android.system.OsConstants; |
| import android.net.ConnectivityManager; |
| import android.net.NetworkUtils; |
| import android.net.util.IpUtils; |
| |
| 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 { |
| /** Protocol of the packet to send; one of the OsConstants.ETH_P_* values. */ |
| public final int protocol; |
| |
| /** 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; |
| |
| /** Destination MAC address. Can change if routing changes. */ |
| public byte[] dstMac; |
| |
| /** Packet data. A raw byte string of packet data, not including the link-layer header. */ |
| public final byte[] data; |
| |
| private static final int IPV4_HEADER_LENGTH = 20; |
| private static final int UDP_HEADER_LENGTH = 8; |
| |
| 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.data = data; |
| |
| // Check we have two IP addresses of the same family. |
| if (srcAddress == null || dstAddress == null || |
| !srcAddress.getClass().getName().equals(dstAddress.getClass().getName())) { |
| throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS); |
| } |
| |
| // Set the protocol. |
| if (this.dstAddress instanceof Inet4Address) { |
| this.protocol = OsConstants.ETH_P_IP; |
| } else if (this.dstAddress instanceof Inet6Address) { |
| this.protocol = OsConstants.ETH_P_IPV6; |
| } else { |
| throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS); |
| } |
| |
| // Check the ports. |
| if (!IpUtils.isValidUdpOrTcpPort(srcPort) || !IpUtils.isValidUdpOrTcpPort(dstPort)) { |
| throw new InvalidPacketException(ERROR_INVALID_PORT); |
| } |
| } |
| |
| public static class InvalidPacketException extends Exception { |
| final public int error; |
| public InvalidPacketException(int error) { |
| this.error = error; |
| } |
| } |
| |
| /** |
| * Creates an IPsec NAT-T keepalive packet with the specified parameters. |
| */ |
| public static KeepalivePacketData nattKeepalivePacket( |
| InetAddress srcAddress, int srcPort, |
| InetAddress dstAddress, int dstPort) throws InvalidPacketException { |
| |
| 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()); |
| } |
| } |