1 /* 2 * Copyright (C) 2024 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.server.wifi.nl80211; 18 19 import android.annotation.NonNull; 20 import android.annotation.Nullable; 21 22 import java.nio.ByteBuffer; 23 import java.util.Objects; 24 25 /** 26 * Representation of a generic Netlink message header. 27 * 28 * See kernel/uapi/linux/genetlink.h 29 */ 30 public class StructGenNlMsgHdr { 31 public static final int STRUCT_SIZE = 4; 32 33 public final short command; // byte 34 public final byte version; 35 public final short reserved; 36 StructGenNlMsgHdr(short command)37 public StructGenNlMsgHdr(short command) { 38 this.command = command; 39 this.version = 1; // only V1 is used 40 this.reserved = 0; // unused 41 } 42 StructGenNlMsgHdr(short command, byte version, short reserved)43 private StructGenNlMsgHdr(short command, byte version, short reserved) { 44 this.command = command; 45 this.version = version; 46 this.reserved = reserved; 47 } 48 49 /** 50 * Read a StructGenNlMsgHdr object from a ByteBuffer. 51 */ 52 @Nullable parse(@onNull final ByteBuffer byteBuffer)53 public static StructGenNlMsgHdr parse(@NonNull final ByteBuffer byteBuffer) { 54 if (byteBuffer == null || byteBuffer.remaining() < STRUCT_SIZE) { 55 return null; 56 } 57 // Assume that the byte buffer has already been set to native order 58 short command = (short) (byteBuffer.get() & 0xFF); 59 byte version = byteBuffer.get(); 60 short reserved = byteBuffer.getShort(); 61 return new StructGenNlMsgHdr(command, version, reserved); 62 } 63 64 /** 65 * Write a StructGenNlMsgHdr object to a ByteBuffer. 66 */ pack(@onNull final ByteBuffer byteBuffer)67 public void pack(@NonNull final ByteBuffer byteBuffer) { 68 if (byteBuffer == null || byteBuffer.remaining() < STRUCT_SIZE) { 69 return; 70 } 71 // Assume that the byte buffer has already been set to native order 72 byteBuffer.put((byte) (command & 0xFF)); 73 byteBuffer.put(version); 74 byteBuffer.putShort(reserved); 75 } 76 77 @Override equals(Object o)78 public boolean equals(Object o) { 79 if (o == this) return true; 80 if (o == null || !(o instanceof StructGenNlMsgHdr)) return false; 81 StructGenNlMsgHdr other = (StructGenNlMsgHdr) o; 82 return this.command == other.command 83 && this.version == other.version 84 && this.reserved == other.reserved; 85 } 86 87 @Override hashCode()88 public int hashCode() { 89 return Objects.hash(command, version, reserved); 90 } 91 92 @Override toString()93 public String toString() { 94 return "StructGenNlMsgHdr{ " 95 + "command{" + command + "}, " 96 + "version{" + version + "}, " 97 + "reserved{" + reserved + "} " 98 + "}"; 99 } 100 } 101