Erik Kline | 6193aa3 | 2015-01-20 12:28:26 +0900 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2015 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 android.net.netlink; |
| 18 | |
| 19 | import android.net.netlink.NetlinkConstants; |
| 20 | import libcore.io.SizeOf; |
| 21 | |
| 22 | import java.net.InetAddress; |
| 23 | import java.net.UnknownHostException; |
| 24 | import java.nio.ByteOrder; |
| 25 | import java.nio.ByteBuffer; |
| 26 | |
| 27 | |
| 28 | /** |
| 29 | * struct nlattr |
| 30 | * |
| 31 | * see: <linux_src>/include/uapi/linux/netlink.h |
| 32 | * |
| 33 | * @hide |
| 34 | */ |
| 35 | public class StructNlAttr { |
| 36 | // Already aligned. |
| 37 | public static final int NLA_HEADERLEN = 4; |
| 38 | |
| 39 | // Return a (length, type) object only, without consuming any bytes in |
| 40 | // |byteBuffer| and without copying or interpreting any value bytes. |
| 41 | // This is used for scanning over a packed set of struct nlattr's, |
| 42 | // looking for instances of a particular type. |
| 43 | public static StructNlAttr peek(ByteBuffer byteBuffer) { |
| 44 | if (byteBuffer == null || byteBuffer.remaining() < NLA_HEADERLEN) { |
| 45 | return null; |
| 46 | } |
| 47 | final int baseOffset = byteBuffer.position(); |
| 48 | |
| 49 | final StructNlAttr struct = new StructNlAttr(); |
| 50 | struct.nla_len = byteBuffer.getShort(); |
| 51 | struct.nla_type = byteBuffer.getShort(); |
| 52 | struct.mByteOrder = byteBuffer.order(); |
| 53 | |
| 54 | byteBuffer.position(baseOffset); |
| 55 | if (struct.nla_len < NLA_HEADERLEN) { |
| 56 | // Malformed. |
| 57 | return null; |
| 58 | } |
| 59 | return struct; |
| 60 | } |
| 61 | |
| 62 | public static StructNlAttr parse(ByteBuffer byteBuffer) { |
| 63 | final StructNlAttr struct = peek(byteBuffer); |
| 64 | if (struct == null || byteBuffer.remaining() < struct.getAlignedLength()) { |
| 65 | return null; |
| 66 | } |
| 67 | |
| 68 | final int baseOffset = byteBuffer.position(); |
| 69 | byteBuffer.position(baseOffset + NLA_HEADERLEN); |
| 70 | |
| 71 | int valueLen = ((int) struct.nla_len) & 0xffff; |
| 72 | valueLen -= NLA_HEADERLEN; |
| 73 | if (valueLen > 0) { |
| 74 | struct.nla_value = new byte[valueLen]; |
| 75 | byteBuffer.get(struct.nla_value, 0, valueLen); |
| 76 | byteBuffer.position(baseOffset + struct.getAlignedLength()); |
| 77 | } |
| 78 | return struct; |
| 79 | } |
| 80 | |
| 81 | public short nla_len; |
| 82 | public short nla_type; |
| 83 | public byte[] nla_value; |
| 84 | public ByteOrder mByteOrder; |
| 85 | |
| 86 | public StructNlAttr() { |
| 87 | mByteOrder = ByteOrder.nativeOrder(); |
| 88 | } |
| 89 | |
| 90 | public int getAlignedLength() { |
| 91 | return NetlinkConstants.alignedLengthOf(nla_len); |
| 92 | } |
| 93 | |
| 94 | public ByteBuffer getValueAsByteBuffer() { |
| 95 | if (nla_value == null) { return null; } |
| 96 | final ByteBuffer byteBuffer = ByteBuffer.wrap(nla_value); |
| 97 | byteBuffer.order(mByteOrder); |
| 98 | return byteBuffer; |
| 99 | } |
| 100 | |
| 101 | public int getValueAsInt(int defaultValue) { |
| 102 | final ByteBuffer byteBuffer = getValueAsByteBuffer(); |
| 103 | if (byteBuffer == null || byteBuffer.remaining() != SizeOf.INT) { |
| 104 | return defaultValue; |
| 105 | } |
| 106 | return getValueAsByteBuffer().getInt(); |
| 107 | } |
| 108 | |
| 109 | public InetAddress getValueAsInetAddress() { |
| 110 | if (nla_value == null) { return null; } |
| 111 | |
| 112 | try { |
| 113 | return InetAddress.getByAddress(nla_value); |
| 114 | } catch (UnknownHostException ignored) { |
| 115 | return null; |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | @Override |
| 120 | public String toString() { |
| 121 | return "StructNlAttr{ " |
| 122 | + "nla_len{" + nla_len + "}, " |
| 123 | + "nla_type{" + nla_type + "}, " |
| 124 | + "nla_value{" + NetlinkConstants.hexify(nla_value) + "}, " |
| 125 | + "}"; |
| 126 | } |
| 127 | } |