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/*
* 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.system.OsConstants;
import java.nio.ByteBuffer;
/**
* struct ndmsg
*
* see: <linux_src>/include/uapi/linux/neighbour.h
*
* @hide
*/
public class StructNdMsg {
// Already aligned.
public static final int STRUCT_SIZE = 12;
// Neighbor Cache Entry States
public static final short NUD_NONE = 0x00;
public static final short NUD_INCOMPLETE = 0x01;
public static final short NUD_REACHABLE = 0x02;
public static final short NUD_STALE = 0x04;
public static final short NUD_DELAY = 0x08;
public static final short NUD_PROBE = 0x10;
public static final short NUD_FAILED = 0x20;
public static final short NUD_NOARP = 0x40;
public static final short NUD_PERMANENT = 0x80;
/**
* Convert neighbor cache entry state integer to string.
*/
public static String stringForNudState(short nudState) {
switch (nudState) {
case NUD_NONE: return "NUD_NONE";
case NUD_INCOMPLETE: return "NUD_INCOMPLETE";
case NUD_REACHABLE: return "NUD_REACHABLE";
case NUD_STALE: return "NUD_STALE";
case NUD_DELAY: return "NUD_DELAY";
case NUD_PROBE: return "NUD_PROBE";
case NUD_FAILED: return "NUD_FAILED";
case NUD_NOARP: return "NUD_NOARP";
case NUD_PERMANENT: return "NUD_PERMANENT";
default:
return "unknown NUD state: " + String.valueOf(nudState);
}
}
/**
* Check whether a neighbor is connected or not.
*/
public static boolean isNudStateConnected(short nudState) {
return ((nudState & (NUD_PERMANENT | NUD_NOARP | NUD_REACHABLE)) != 0);
}
/**
* Check whether a neighbor is in the valid NUD state or not.
*/
public static boolean isNudStateValid(short nudState) {
return (isNudStateConnected(nudState)
|| ((nudState & (NUD_PROBE | NUD_STALE | NUD_DELAY)) != 0));
}
// Neighbor Cache Entry Flags
public static byte NTF_USE = (byte) 0x01;
public static byte NTF_SELF = (byte) 0x02;
public static byte NTF_MASTER = (byte) 0x04;
public static byte NTF_PROXY = (byte) 0x08;
public static byte NTF_ROUTER = (byte) 0x80;
private static String stringForNudFlags(byte flags) {
final StringBuilder sb = new StringBuilder();
if ((flags & NTF_USE) != 0) {
sb.append("NTF_USE");
}
if ((flags & NTF_SELF) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NTF_SELF");
}
if ((flags & NTF_MASTER) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NTF_MASTER");
}
if ((flags & NTF_PROXY) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NTF_PROXY");
}
if ((flags & NTF_ROUTER) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NTF_ROUTER");
}
return sb.toString();
}
private static boolean hasAvailableSpace(ByteBuffer byteBuffer) {
return byteBuffer != null && byteBuffer.remaining() >= STRUCT_SIZE;
}
/**
* Parse a neighbor discovery netlink message header from a {@link ByteBuffer}.
*
* @param byteBuffer The buffer from which to parse the nd netlink message header.
* @return the parsed nd netlink message header, or {@code null} if the nd netlink message
* header could not be parsed successfully (for example, if it was truncated).
*/
public static StructNdMsg parse(ByteBuffer byteBuffer) {
if (!hasAvailableSpace(byteBuffer)) return null;
// The ByteOrder must have already been set by the caller. In most
// cases ByteOrder.nativeOrder() is correct, with the possible
// exception of usage within unittests.
final StructNdMsg struct = new StructNdMsg();
struct.ndm_family = byteBuffer.get();
final byte pad1 = byteBuffer.get();
final short pad2 = byteBuffer.getShort();
struct.ndm_ifindex = byteBuffer.getInt();
struct.ndm_state = byteBuffer.getShort();
struct.ndm_flags = byteBuffer.get();
struct.ndm_type = byteBuffer.get();
return struct;
}
public byte ndm_family;
public int ndm_ifindex;
public short ndm_state;
public byte ndm_flags;
public byte ndm_type;
public StructNdMsg() {
ndm_family = (byte) OsConstants.AF_UNSPEC;
}
/**
* Write the neighbor discovery message header to {@link ByteBuffer}.
*/
public void pack(ByteBuffer byteBuffer) {
// The ByteOrder must have already been set by the caller. In most
// cases ByteOrder.nativeOrder() is correct, with the exception
// of usage within unittests.
byteBuffer.put(ndm_family);
byteBuffer.put((byte) 0); // pad1
byteBuffer.putShort((short) 0); // pad2
byteBuffer.putInt(ndm_ifindex);
byteBuffer.putShort(ndm_state);
byteBuffer.put(ndm_flags);
byteBuffer.put(ndm_type);
}
/**
* Check whether a neighbor is connected or not.
*/
public boolean nudConnected() {
return isNudStateConnected(ndm_state);
}
/**
* Check whether a neighbor is in the valid NUD state or not.
*/
public boolean nudValid() {
return isNudStateValid(ndm_state);
}
@Override
public String toString() {
final String stateStr = "" + ndm_state + " (" + stringForNudState(ndm_state) + ")";
final String flagsStr = "" + ndm_flags + " (" + stringForNudFlags(ndm_flags) + ")";
return "StructNdMsg{ "
+ "family{" + NetlinkConstants.stringForAddressFamily((int) ndm_family) + "}, "
+ "ifindex{" + ndm_ifindex + "}, "
+ "state{" + stateStr + "}, "
+ "flags{" + flagsStr + "}, "
+ "type{" + ndm_type + "} "
+ "}";
}
}
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