| /* |
| * Copyright (C) 2017 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.net.module.util.netlink; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.Nullable; |
| |
| import java.nio.ByteBuffer; |
| import java.nio.ByteOrder; |
| import java.util.Objects; |
| |
| /** |
| * struct nfgenmsg |
| * |
| * see <linux_src>/include/uapi/linux/netfilter/nfnetlink.h |
| * |
| * @hide |
| */ |
| public class StructNfGenMsg { |
| public static final int STRUCT_SIZE = 2 + Short.BYTES; |
| |
| public static final int NFNETLINK_V0 = 0; |
| |
| public final byte nfgen_family; |
| public final byte version; |
| public final short res_id; // N.B.: this is big endian in the kernel |
| |
| /** |
| * Parse a netfilter netlink header from a {@link ByteBuffer}. |
| * |
| * @param byteBuffer The buffer from which to parse the netfilter netlink header. |
| * @return the parsed netfilter netlink header, or {@code null} if the netfilter netlink header |
| * could not be parsed successfully (for example, if it was truncated). |
| */ |
| @Nullable |
| public static StructNfGenMsg parse(@NonNull ByteBuffer byteBuffer) { |
| Objects.requireNonNull(byteBuffer); |
| |
| if (!hasAvailableSpace(byteBuffer)) return null; |
| |
| final byte nfgen_family = byteBuffer.get(); |
| final byte version = byteBuffer.get(); |
| |
| final ByteOrder originalOrder = byteBuffer.order(); |
| byteBuffer.order(ByteOrder.BIG_ENDIAN); |
| final short res_id = byteBuffer.getShort(); |
| byteBuffer.order(originalOrder); |
| |
| return new StructNfGenMsg(nfgen_family, version, res_id); |
| } |
| |
| public StructNfGenMsg(byte family, byte ver, short id) { |
| nfgen_family = family; |
| version = ver; |
| res_id = id; |
| } |
| |
| public StructNfGenMsg(byte family) { |
| nfgen_family = family; |
| version = (byte) NFNETLINK_V0; |
| res_id = (short) 0; |
| } |
| |
| /** |
| * Write a netfilter netlink header to a {@link ByteBuffer}. |
| */ |
| public void pack(ByteBuffer byteBuffer) { |
| byteBuffer.put(nfgen_family); |
| byteBuffer.put(version); |
| |
| final ByteOrder originalOrder = byteBuffer.order(); |
| byteBuffer.order(ByteOrder.BIG_ENDIAN); |
| byteBuffer.putShort(res_id); |
| byteBuffer.order(originalOrder); |
| } |
| |
| private static boolean hasAvailableSpace(@NonNull ByteBuffer byteBuffer) { |
| return byteBuffer.remaining() >= STRUCT_SIZE; |
| } |
| |
| @Override |
| public String toString() { |
| final String familyStr = NetlinkConstants.stringForAddressFamily(nfgen_family); |
| |
| return "NfGenMsg{ " |
| + "nfgen_family{" + familyStr + "}, " |
| + "version{" + Byte.toUnsignedInt(version) + "}, " |
| + "res_id{" + Short.toUnsignedInt(res_id) + "} " |
| + "}"; |
| } |
| } |