1 /* 2 * Copyright (C) 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.net.module.util.netlink; 18 19 import java.nio.ByteBuffer; 20 21 /** 22 * struct nlmsgerr 23 * 24 * see <linux_src>/include/uapi/linux/netlink.h 25 * 26 * @hide 27 */ 28 public class StructNlMsgErr { 29 public static final int STRUCT_SIZE = Integer.BYTES + StructNlMsgHdr.STRUCT_SIZE; 30 hasAvailableSpace(ByteBuffer byteBuffer)31 private static boolean hasAvailableSpace(ByteBuffer byteBuffer) { 32 return byteBuffer != null && byteBuffer.remaining() >= STRUCT_SIZE; 33 } 34 35 /** 36 * Parse a netlink error message payload from a {@link ByteBuffer}. 37 * 38 * @param byteBuffer The buffer from which to parse the netlink error message payload. 39 * @return the parsed netlink error message payload, or {@code null} if the netlink error 40 * message payload could not be parsed successfully (for example, if it was truncated). 41 */ parse(ByteBuffer byteBuffer)42 public static StructNlMsgErr parse(ByteBuffer byteBuffer) { 43 if (!hasAvailableSpace(byteBuffer)) return null; 44 45 // The ByteOrder must have already been set by the caller. In most 46 // cases ByteOrder.nativeOrder() is correct, with the exception 47 // of usage within unittests. 48 final StructNlMsgErr struct = new StructNlMsgErr(); 49 struct.error = byteBuffer.getInt(); 50 struct.msg = StructNlMsgHdr.parse(byteBuffer); 51 return struct; 52 } 53 54 public int error; 55 public StructNlMsgHdr msg; 56 57 /** 58 * Write the netlink error message payload to {@link ByteBuffer}. 59 */ pack(ByteBuffer byteBuffer)60 public void pack(ByteBuffer byteBuffer) { 61 // The ByteOrder must have already been set by the caller. In most 62 // cases ByteOrder.nativeOrder() is correct, with the possible 63 // exception of usage within unittests. 64 byteBuffer.putInt(error); 65 if (msg != null) { 66 msg.pack(byteBuffer); 67 } 68 } 69 70 @Override toString()71 public String toString() { 72 return "StructNlMsgErr{ " 73 + "error{" + error + "}, " 74 + "msg{" + (msg == null ? "" : msg.toString()) + "} " 75 + "}"; 76 } 77 } 78