| /* |
| * 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 com.android.net.module.util.netlink; |
| |
| import android.net.MacAddress; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.Nullable; |
| |
| import java.io.UnsupportedEncodingException; |
| import java.net.InetAddress; |
| import java.net.UnknownHostException; |
| import java.nio.ByteBuffer; |
| import java.nio.ByteOrder; |
| import java.util.Arrays; |
| |
| /** |
| * struct nlattr |
| * |
| * see: <linux_src>/include/uapi/linux/netlink.h |
| * |
| * @hide |
| */ |
| public class StructNlAttr { |
| // Already aligned. |
| public static final int NLA_HEADERLEN = 4; |
| public static final int NLA_F_NESTED = (1 << 15); |
| |
| /** |
| * Set carries nested attributes bit. |
| */ |
| public static short makeNestedType(short type) { |
| return (short) (type | NLA_F_NESTED); |
| } |
| |
| /** |
| * Peek and parse the netlink attribute from {@link ByteBuffer}. |
| * |
| * Return a (length, type) object only, without consuming any bytes in |
| * |byteBuffer| and without copying or interpreting any value bytes. |
| * This is used for scanning over a packed set of struct nlattr's, |
| * looking for instances of a particular type. |
| */ |
| public static StructNlAttr peek(ByteBuffer byteBuffer) { |
| if (byteBuffer == null || byteBuffer.remaining() < NLA_HEADERLEN) { |
| return null; |
| } |
| final int baseOffset = byteBuffer.position(); |
| |
| final StructNlAttr struct = new StructNlAttr(); |
| final ByteOrder originalOrder = byteBuffer.order(); |
| byteBuffer.order(ByteOrder.nativeOrder()); |
| try { |
| struct.nla_len = byteBuffer.getShort(); |
| struct.nla_type = byteBuffer.getShort(); |
| } finally { |
| byteBuffer.order(originalOrder); |
| } |
| |
| byteBuffer.position(baseOffset); |
| if (struct.nla_len < NLA_HEADERLEN) { |
| // Malformed. |
| return null; |
| } |
| return struct; |
| } |
| |
| /** |
| * Parse a netlink attribute from a {@link ByteBuffer}. |
| * |
| * @param byteBuffer The buffer from which to parse the netlink attriute. |
| * @return the parsed netlink attribute, or {@code null} if the netlink attribute |
| * could not be parsed successfully (for example, if it was truncated). |
| */ |
| public static StructNlAttr parse(ByteBuffer byteBuffer) { |
| final StructNlAttr struct = peek(byteBuffer); |
| if (struct == null || byteBuffer.remaining() < struct.getAlignedLength()) { |
| return null; |
| } |
| |
| final int baseOffset = byteBuffer.position(); |
| byteBuffer.position(baseOffset + NLA_HEADERLEN); |
| |
| int valueLen = ((int) struct.nla_len) & 0xffff; |
| valueLen -= NLA_HEADERLEN; |
| if (valueLen > 0) { |
| struct.nla_value = new byte[valueLen]; |
| byteBuffer.get(struct.nla_value, 0, valueLen); |
| byteBuffer.position(baseOffset + struct.getAlignedLength()); |
| } |
| return struct; |
| } |
| |
| /** |
| * Find next netlink attribute with a given type from {@link ByteBuffer}. |
| * |
| * @param attrType The given netlink attribute type is requested for. |
| * @param byteBuffer The buffer from which to find the netlink attribute. |
| * @return the found netlink attribute, or {@code null} if the netlink attribute could not be |
| * found or parsed successfully (for example, if it was truncated). |
| */ |
| @Nullable |
| public static StructNlAttr findNextAttrOfType(short attrType, |
| @Nullable ByteBuffer byteBuffer) { |
| while (byteBuffer != null && byteBuffer.remaining() > 0) { |
| final StructNlAttr nlAttr = StructNlAttr.peek(byteBuffer); |
| if (nlAttr == null) { |
| break; |
| } |
| if (nlAttr.nla_type == attrType) { |
| return StructNlAttr.parse(byteBuffer); |
| } |
| if (byteBuffer.remaining() < nlAttr.getAlignedLength()) { |
| break; |
| } |
| byteBuffer.position(byteBuffer.position() + nlAttr.getAlignedLength()); |
| } |
| return null; |
| } |
| |
| public short nla_len = (short) NLA_HEADERLEN; |
| public short nla_type; |
| public byte[] nla_value; |
| |
| public StructNlAttr() {} |
| |
| public StructNlAttr(short type, byte value) { |
| nla_type = type; |
| setValue(new byte[1]); |
| nla_value[0] = value; |
| } |
| |
| public StructNlAttr(short type, short value) { |
| this(type, value, ByteOrder.nativeOrder()); |
| } |
| |
| public StructNlAttr(short type, short value, ByteOrder order) { |
| nla_type = type; |
| setValue(new byte[Short.BYTES]); |
| final ByteBuffer buf = getValueAsByteBuffer(); |
| final ByteOrder originalOrder = buf.order(); |
| try { |
| buf.order(order); |
| buf.putShort(value); |
| } finally { |
| buf.order(originalOrder); |
| } |
| } |
| |
| public StructNlAttr(short type, int value) { |
| this(type, value, ByteOrder.nativeOrder()); |
| } |
| |
| public StructNlAttr(short type, int value, ByteOrder order) { |
| nla_type = type; |
| setValue(new byte[Integer.BYTES]); |
| final ByteBuffer buf = getValueAsByteBuffer(); |
| final ByteOrder originalOrder = buf.order(); |
| try { |
| buf.order(order); |
| buf.putInt(value); |
| } finally { |
| buf.order(originalOrder); |
| } |
| } |
| |
| public StructNlAttr(short type, @NonNull final byte[] value) { |
| nla_type = type; |
| setValue(value); |
| } |
| |
| public StructNlAttr(short type, @NonNull final InetAddress ip) { |
| nla_type = type; |
| setValue(ip.getAddress()); |
| } |
| |
| public StructNlAttr(short type, @NonNull final MacAddress mac) { |
| nla_type = type; |
| setValue(mac.toByteArray()); |
| } |
| |
| public StructNlAttr(short type, @NonNull final String string) { |
| nla_type = type; |
| byte[] value = null; |
| try { |
| final byte[] stringBytes = string.getBytes("UTF-8"); |
| // Append '\0' at the end of interface name string bytes. |
| value = Arrays.copyOf(stringBytes, stringBytes.length + 1); |
| } catch (UnsupportedEncodingException ignored) { |
| // Do nothing. |
| } finally { |
| setValue(value); |
| } |
| } |
| |
| public StructNlAttr(short type, StructNlAttr... nested) { |
| this(); |
| nla_type = makeNestedType(type); |
| |
| int payloadLength = 0; |
| for (StructNlAttr nla : nested) payloadLength += nla.getAlignedLength(); |
| setValue(new byte[payloadLength]); |
| |
| final ByteBuffer buf = getValueAsByteBuffer(); |
| for (StructNlAttr nla : nested) { |
| nla.pack(buf); |
| } |
| } |
| |
| /** |
| * Get aligned attribute length. |
| */ |
| public int getAlignedLength() { |
| return NetlinkConstants.alignedLengthOf(nla_len); |
| } |
| |
| /** |
| * Get attribute value as BE16. |
| */ |
| public short getValueAsBe16(short defaultValue) { |
| final ByteBuffer byteBuffer = getValueAsByteBuffer(); |
| if (byteBuffer == null || byteBuffer.remaining() != Short.BYTES) { |
| return defaultValue; |
| } |
| final ByteOrder originalOrder = byteBuffer.order(); |
| try { |
| byteBuffer.order(ByteOrder.BIG_ENDIAN); |
| return byteBuffer.getShort(); |
| } finally { |
| byteBuffer.order(originalOrder); |
| } |
| } |
| |
| /** |
| * Get attribute value as BE32. |
| */ |
| public int getValueAsBe32(int defaultValue) { |
| final ByteBuffer byteBuffer = getValueAsByteBuffer(); |
| if (byteBuffer == null || byteBuffer.remaining() != Integer.BYTES) { |
| return defaultValue; |
| } |
| final ByteOrder originalOrder = byteBuffer.order(); |
| try { |
| byteBuffer.order(ByteOrder.BIG_ENDIAN); |
| return byteBuffer.getInt(); |
| } finally { |
| byteBuffer.order(originalOrder); |
| } |
| } |
| |
| /** |
| * Get attribute value as ByteBuffer. |
| */ |
| public ByteBuffer getValueAsByteBuffer() { |
| if (nla_value == null) return null; |
| final ByteBuffer byteBuffer = ByteBuffer.wrap(nla_value); |
| // By convention, all buffers in this library are in native byte order because netlink is in |
| // native byte order. It's the order that is used by NetlinkSocket.recvMessage and the only |
| // order accepted by NetlinkMessage.parse. |
| byteBuffer.order(ByteOrder.nativeOrder()); |
| return byteBuffer; |
| } |
| |
| /** |
| * Get attribute value as byte. |
| */ |
| public byte getValueAsByte(byte defaultValue) { |
| final ByteBuffer byteBuffer = getValueAsByteBuffer(); |
| if (byteBuffer == null || byteBuffer.remaining() != Byte.BYTES) { |
| return defaultValue; |
| } |
| return getValueAsByteBuffer().get(); |
| } |
| |
| /** |
| * Get attribute value as Integer, or null if malformed (e.g., length is not 4 bytes). |
| */ |
| public Integer getValueAsInteger() { |
| final ByteBuffer byteBuffer = getValueAsByteBuffer(); |
| if (byteBuffer == null || byteBuffer.remaining() != Integer.BYTES) { |
| return null; |
| } |
| return byteBuffer.getInt(); |
| } |
| |
| /** |
| * Get attribute value as Int, default value if malformed. |
| */ |
| public int getValueAsInt(int defaultValue) { |
| final Integer value = getValueAsInteger(); |
| return (value != null) ? value : defaultValue; |
| } |
| |
| /** |
| * Get attribute value as InetAddress. |
| * |
| * @return the InetAddress instance representation of attribute value or null if IP address |
| * is of illegal length. |
| */ |
| @Nullable |
| public InetAddress getValueAsInetAddress() { |
| if (nla_value == null) return null; |
| |
| try { |
| return InetAddress.getByAddress(nla_value); |
| } catch (UnknownHostException ignored) { |
| return null; |
| } |
| } |
| |
| /** |
| * Get attribute value as MacAddress. |
| * |
| * @return the MacAddress instance representation of attribute value or null if the given byte |
| * array is not a valid representation(e.g, not all link layers have 6-byte link-layer |
| * addresses) |
| */ |
| @Nullable |
| public MacAddress getValueAsMacAddress() { |
| if (nla_value == null) return null; |
| |
| try { |
| return MacAddress.fromBytes(nla_value); |
| } catch (IllegalArgumentException ignored) { |
| return null; |
| } |
| } |
| |
| /** |
| * Get attribute value as a unicode string. |
| * |
| * @return a unicode string or null if UTF-8 charset is not supported. |
| */ |
| @Nullable |
| public String getValueAsString() { |
| if (nla_value == null) return null; |
| // Check the attribute value length after removing string termination flag '\0'. |
| // This assumes that all netlink strings are null-terminated. |
| if (nla_value.length < (nla_len - NLA_HEADERLEN - 1)) return null; |
| |
| try { |
| final byte[] array = Arrays.copyOf(nla_value, nla_len - NLA_HEADERLEN - 1); |
| return new String(array, "UTF-8"); |
| } catch (UnsupportedEncodingException | NegativeArraySizeException ignored) { |
| return null; |
| } |
| } |
| |
| /** |
| * Write the netlink attribute to {@link ByteBuffer}. |
| */ |
| public void pack(ByteBuffer byteBuffer) { |
| final ByteOrder originalOrder = byteBuffer.order(); |
| final int originalPosition = byteBuffer.position(); |
| |
| byteBuffer.order(ByteOrder.nativeOrder()); |
| try { |
| byteBuffer.putShort(nla_len); |
| byteBuffer.putShort(nla_type); |
| if (nla_value != null) byteBuffer.put(nla_value); |
| } finally { |
| byteBuffer.order(originalOrder); |
| } |
| byteBuffer.position(originalPosition + getAlignedLength()); |
| } |
| |
| private void setValue(byte[] value) { |
| nla_value = value; |
| nla_len = (short) (NLA_HEADERLEN + ((nla_value != null) ? nla_value.length : 0)); |
| } |
| |
| @Override |
| public String toString() { |
| return "StructNlAttr{ " |
| + "nla_len{" + nla_len + "}, " |
| + "nla_type{" + nla_type + "}, " |
| + "nla_value{" + NetlinkConstants.hexify(nla_value) + "}, " |
| + "}"; |
| } |
| } |