| /* |
| * Copyright (C) 2019 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 static android.net.InvalidPacketException.ERROR_INVALID_IP_ADDRESS; |
| import static android.net.InvalidPacketException.ERROR_INVALID_PORT; |
| |
| import android.annotation.NonNull; |
| import android.annotation.SystemApi; |
| import android.net.util.IpUtils; |
| import android.os.Parcel; |
| import android.os.Parcelable; |
| import android.system.OsConstants; |
| |
| import java.net.Inet4Address; |
| import java.net.InetAddress; |
| import java.nio.ByteBuffer; |
| import java.nio.ByteOrder; |
| |
| /** @hide */ |
| @SystemApi |
| public final class NattKeepalivePacketData extends KeepalivePacketData implements Parcelable { |
| 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 |
| public NattKeepalivePacketData(@NonNull InetAddress srcAddress, int srcPort, |
| @NonNull InetAddress dstAddress, int dstPort, @NonNull byte[] data) throws |
| InvalidPacketException { |
| super(srcAddress, srcPort, dstAddress, dstPort, data); |
| } |
| |
| /** |
| * Factory method to create Nat-T keepalive packet structure. |
| * @hide |
| */ |
| public static NattKeepalivePacketData 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 != NattSocketKeepalive.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 NattKeepalivePacketData(srcAddress, srcPort, dstAddress, dstPort, buf.array()); |
| } |
| |
| /** Parcelable Implementation */ |
| public int describeContents() { |
| return 0; |
| } |
| |
| /** Write to parcel */ |
| public void writeToParcel(@NonNull Parcel out, int flags) { |
| out.writeString(srcAddress.getHostAddress()); |
| out.writeString(dstAddress.getHostAddress()); |
| out.writeInt(srcPort); |
| out.writeInt(dstPort); |
| } |
| |
| /** Parcelable Creator */ |
| public static final @NonNull Parcelable.Creator<NattKeepalivePacketData> CREATOR = |
| new Parcelable.Creator<NattKeepalivePacketData>() { |
| public NattKeepalivePacketData createFromParcel(Parcel in) { |
| final InetAddress srcAddress = |
| InetAddresses.parseNumericAddress(in.readString()); |
| final InetAddress dstAddress = |
| InetAddresses.parseNumericAddress(in.readString()); |
| final int srcPort = in.readInt(); |
| final int dstPort = in.readInt(); |
| try { |
| return NattKeepalivePacketData.nattKeepalivePacket(srcAddress, srcPort, |
| dstAddress, dstPort); |
| } catch (InvalidPacketException e) { |
| throw new IllegalArgumentException( |
| "Invalid NAT-T keepalive data: " + e.error); |
| } |
| } |
| |
| public NattKeepalivePacketData[] newArray(int size) { |
| return new NattKeepalivePacketData[size]; |
| } |
| }; |
| } |