StructNdMsg.java revision 6193aa3305bc2aa5b7f0a983f4b08c99065cfb82 
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
17package android.net.netlink;
18
19import android.net.netlink.NetlinkConstants;
20import android.system.OsConstants;
21import java.nio.ByteBuffer;
22
23
24/**
25 * struct ndmsg
26 *
27 * see: <linux_src>/include/uapi/linux/neighbour.h
28 *
29 * @hide
30 */
31public class StructNdMsg {
32    // Already aligned.
33    public static final int STRUCT_SIZE = 12;
34
35    // Neighbor Cache Entry States
36    public static final short NUD_INCOMPLETE  = 0x01;
37    public static final short NUD_REACHABLE   = 0x02;
38    public static final short NUD_STALE       = 0x04;
39    public static final short NUD_DELAY       = 0x08;
40    public static final short NUD_PROBE       = 0x10;
41    public static final short NUD_FAILED      = 0x20;
42    public static final short NUD_NOARP       = 0x40;
43    public static final short NUD_PERMANENT   = 0x80;
44
45    public static String stringForNudState(short nudState) {
46        switch (nudState) {
47            case NUD_INCOMPLETE: return "NUD_INCOMPLETE";
48            case NUD_REACHABLE: return "NUD_REACHABLE";
49            case NUD_STALE: return "NUD_STALE";
50            case NUD_DELAY: return "NUD_DELAY";
51            case NUD_PROBE: return "NUD_PROBE";
52            case NUD_FAILED: return "NUD_FAILED";
53            case NUD_NOARP: return "NUD_NOARP";
54            case NUD_PERMANENT: return "NUD_PERMANENT";
55            default:
56                return "unknown NUD state: " + String.valueOf(nudState);
57        }
58    }
59
60    public static boolean isNudStateConnected(short nudState) {
61        return ((nudState & (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE)) != 0);
62    }
63
64    // Neighbor Cache Entry Flags
65    public static byte NTF_USE       = (byte) 0x01;
66    public static byte NTF_SELF      = (byte) 0x02;
67    public static byte NTF_MASTER    = (byte) 0x04;
68    public static byte NTF_PROXY     = (byte) 0x08;
69    public static byte NTF_ROUTER    = (byte) 0x80;
70
71    public static String stringForNudFlags(byte flags) {
72        final StringBuilder sb = new StringBuilder();
73        if ((flags & NTF_USE) != 0) {
74            sb.append("NTF_USE");
75        }
76        if ((flags & NTF_SELF) != 0) {
77            if (sb.length() > 0) { sb.append("|"); }
78            sb.append("NTF_SELF");
79        }
80        if ((flags & NTF_MASTER) != 0) {
81            if (sb.length() > 0) { sb.append("|"); }
82            sb.append("NTF_MASTER");
83        }
84        if ((flags & NTF_PROXY) != 0) {
85            if (sb.length() > 0) { sb.append("|");
86        }
87            sb.append("NTF_PROXY"); }
88        if ((flags & NTF_ROUTER) != 0) {
89            if (sb.length() > 0) { sb.append("|"); }
90            sb.append("NTF_ROUTER");
91        }
92        return sb.toString();
93    }
94
95    private static boolean hasAvailableSpace(ByteBuffer byteBuffer) {
96        return byteBuffer != null && byteBuffer.remaining() >= STRUCT_SIZE;
97    }
98
99    public static StructNdMsg parse(ByteBuffer byteBuffer) {
100        if (!hasAvailableSpace(byteBuffer)) { return null; }
101
102        // The ByteOrder must have already been set by the caller.  In most
103        // cases ByteOrder.nativeOrder() is correct, with the possible
104        // exception of usage within unittests.
105        final StructNdMsg struct = new StructNdMsg();
106        struct.ndm_family = byteBuffer.get();
107        final byte pad1 = byteBuffer.get();
108        final short pad2 = byteBuffer.getShort();
109        struct.ndm_ifindex = byteBuffer.getInt();
110        struct.ndm_state = byteBuffer.getShort();
111        struct.ndm_flags = byteBuffer.get();
112        struct.ndm_type = byteBuffer.get();
113        return struct;
114    }
115
116    public byte ndm_family;
117    public int ndm_ifindex;
118    public short ndm_state;
119    public byte ndm_flags;
120    public byte ndm_type;
121
122    public StructNdMsg() {
123        ndm_family = (byte) OsConstants.AF_UNSPEC;
124    }
125
126    public boolean pack(ByteBuffer byteBuffer) {
127        if (!hasAvailableSpace(byteBuffer)) { return false; }
128
129        // The ByteOrder must have already been set by the caller.  In most
130        // cases ByteOrder.nativeOrder() is correct, with the exception
131        // of usage within unittests.
132        byteBuffer.put(ndm_family);
133        byteBuffer.put((byte) 0);         // pad1
134        byteBuffer.putShort((short) 0);   // pad2
135        byteBuffer.putInt(ndm_ifindex);
136        byteBuffer.putShort(ndm_state);
137        byteBuffer.put(ndm_flags);
138        byteBuffer.put(ndm_type);
139        return true;
140    }
141
142    public boolean nudConnected() {
143        return isNudStateConnected(ndm_state);
144    }
145
146    public boolean nudValid() {
147        return (nudConnected() || ((ndm_state & (NUD_PROBE|NUD_STALE|NUD_DELAY)) != 0));
148    }
149
150    @Override
151    public String toString() {
152        final String stateStr = "" + ndm_state + " (" + stringForNudState(ndm_state) + ")";
153        final String flagsStr = "" + ndm_flags + " (" + stringForNudFlags(ndm_flags) + ")";
154        return "StructNdMsg{ "
155                + "family{" + NetlinkConstants.stringForAddressFamily((int) ndm_family) + "}, "
156                + "ifindex{" + ndm_ifindex + "}, "
157                + "state{" + stateStr + "}, "
158                + "flags{" + flagsStr + "}, "
159                + "type{" + ndm_type + "} "
160                + "}";
161    }
162}
163