1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
/*
* 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 androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import java.nio.ByteBuffer;
/**
* struct nlmsghdr
*
* see <linux_src>/include/uapi/linux/netlink.h
*
* @hide
*/
public class StructNlMsgHdr {
// Already aligned.
public static final int STRUCT_SIZE = 16;
public static final short NLM_F_REQUEST = 0x0001;
public static final short NLM_F_MULTI = 0x0002;
public static final short NLM_F_ACK = 0x0004;
public static final short NLM_F_ECHO = 0x0008;
// Flags for a GET request.
public static final short NLM_F_ROOT = 0x0100;
public static final short NLM_F_MATCH = 0x0200;
public static final short NLM_F_DUMP = NLM_F_ROOT | NLM_F_MATCH;
// Flags for a NEW request.
public static final short NLM_F_REPLACE = 0x100;
public static final short NLM_F_EXCL = 0x200;
public static final short NLM_F_CREATE = 0x400;
public static final short NLM_F_APPEND = 0x800;
// TODO: Probably need to distinguish the flags which have the same value. For example,
// NLM_F_MATCH (0x200) and NLM_F_EXCL (0x200).
private static String stringForNlMsgFlags(short flags) {
final StringBuilder sb = new StringBuilder();
if ((flags & NLM_F_REQUEST) != 0) {
sb.append("NLM_F_REQUEST");
}
if ((flags & NLM_F_MULTI) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NLM_F_MULTI");
}
if ((flags & NLM_F_ACK) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NLM_F_ACK");
}
if ((flags & NLM_F_ECHO) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NLM_F_ECHO");
}
if ((flags & NLM_F_ROOT) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NLM_F_ROOT");
}
if ((flags & NLM_F_MATCH) != 0) {
if (sb.length() > 0) {
sb.append("|");
}
sb.append("NLM_F_MATCH");
}
return sb.toString();
}
private static boolean hasAvailableSpace(ByteBuffer byteBuffer) {
return byteBuffer != null && byteBuffer.remaining() >= STRUCT_SIZE;
}
/**
* Parse netlink message header from buffer.
*/
@Nullable
public static StructNlMsgHdr parse(@NonNull 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 exception
// of usage within unittests.
final StructNlMsgHdr struct = new StructNlMsgHdr();
struct.nlmsg_len = byteBuffer.getInt();
struct.nlmsg_type = byteBuffer.getShort();
struct.nlmsg_flags = byteBuffer.getShort();
struct.nlmsg_seq = byteBuffer.getInt();
struct.nlmsg_pid = byteBuffer.getInt();
if (struct.nlmsg_len < STRUCT_SIZE) {
// Malformed.
return null;
}
return struct;
}
public int nlmsg_len;
public short nlmsg_type;
public short nlmsg_flags;
public int nlmsg_seq;
public int nlmsg_pid;
public StructNlMsgHdr() {
nlmsg_len = 0;
nlmsg_type = 0;
nlmsg_flags = 0;
nlmsg_seq = 0;
nlmsg_pid = 0;
}
/**
* Write netlink message header to 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 possible
// exception of usage within unittests.
byteBuffer.putInt(nlmsg_len);
byteBuffer.putShort(nlmsg_type);
byteBuffer.putShort(nlmsg_flags);
byteBuffer.putInt(nlmsg_seq);
byteBuffer.putInt(nlmsg_pid);
}
@Override
public String toString() {
return toString(null /* unknown netlink family */);
}
/**
* Transform a netlink header into a string. The netlink family is required for transforming
* a netlink type integer into a string.
* @param nlFamily netlink family. Using Integer will not incur autoboxing penalties because
* family values are small, and all Integer objects between -128 and 127 are
* statically cached. See Integer.IntegerCache.
* @return A list of header elements.
*/
@NonNull
public String toString(@Nullable Integer nlFamily) {
final String typeStr = "" + nlmsg_type
+ "(" + (nlFamily == null
? "" : NetlinkConstants.stringForNlMsgType(nlmsg_type, nlFamily))
+ ")";
final String flagsStr = "" + nlmsg_flags
+ "(" + stringForNlMsgFlags(nlmsg_flags) + ")";
return "StructNlMsgHdr{ "
+ "nlmsg_len{" + nlmsg_len + "}, "
+ "nlmsg_type{" + typeStr + "}, "
+ "nlmsg_flags{" + flagsStr + "}, "
+ "nlmsg_seq{" + nlmsg_seq + "}, "
+ "nlmsg_pid{" + nlmsg_pid + "} "
+ "}";
}
}
|
