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.system.ErrnoException;
20import android.system.NetlinkSocketAddress;
21import android.system.Os;
22import android.system.OsConstants;
23import android.system.StructTimeval;
24import android.util.Log;
25import libcore.io.IoUtils;
26import libcore.io.Libcore;
27
28import java.io.Closeable;
29import java.io.FileDescriptor;
30import java.io.InterruptedIOException;
31import java.net.SocketAddress;
32import java.net.SocketException;
33import java.nio.ByteBuffer;
34import java.nio.ByteOrder;
35
36
37/**
38 * NetlinkSocket
39 *
40 * A small wrapper class to assist with AF_NETLINK socket operations.
41 *
42 * @hide
43 */
44public class NetlinkSocket implements Closeable {
45    private static final String TAG = "NetlinkSocket";
46    private static final int SOCKET_RECV_BUFSIZE = 64 * 1024;
47    private static final int DEFAULT_RECV_BUFSIZE = 8 * 1024;
48
49    final private FileDescriptor mDescriptor;
50    private NetlinkSocketAddress mAddr;
51    private long mLastRecvTimeoutMs;
52    private long mLastSendTimeoutMs;
53
54    public NetlinkSocket(int nlProto) throws ErrnoException {
55        mDescriptor = Os.socket(
56                OsConstants.AF_NETLINK, OsConstants.SOCK_DGRAM, nlProto);
57
58        Libcore.os.setsockoptInt(
59                mDescriptor, OsConstants.SOL_SOCKET,
60                OsConstants.SO_RCVBUF, SOCKET_RECV_BUFSIZE);
61    }
62
63    public NetlinkSocketAddress getLocalAddress() throws ErrnoException {
64        return (NetlinkSocketAddress) Os.getsockname(mDescriptor);
65    }
66
67    public void bind(NetlinkSocketAddress localAddr) throws ErrnoException, SocketException {
68        Os.bind(mDescriptor, (SocketAddress)localAddr);
69    }
70
71    public void connectTo(NetlinkSocketAddress peerAddr)
72            throws ErrnoException, SocketException {
73        Os.connect(mDescriptor, (SocketAddress) peerAddr);
74    }
75
76    public void connectToKernel() throws ErrnoException, SocketException {
77        connectTo(new NetlinkSocketAddress(0, 0));
78    }
79
80    /**
81     * Wait indefinitely (or until underlying socket error) for a
82     * netlink message of at most DEFAULT_RECV_BUFSIZE size.
83     */
84    public ByteBuffer recvMessage()
85            throws ErrnoException, InterruptedIOException {
86        return recvMessage(DEFAULT_RECV_BUFSIZE, 0);
87    }
88
89    /**
90     * Wait up to |timeoutMs| (or until underlying socket error) for a
91     * netlink message of at most DEFAULT_RECV_BUFSIZE size.
92     */
93    public ByteBuffer recvMessage(long timeoutMs) throws ErrnoException, InterruptedIOException {
94        return recvMessage(DEFAULT_RECV_BUFSIZE, timeoutMs);
95    }
96
97    private void checkTimeout(long timeoutMs) {
98        if (timeoutMs < 0) {
99            throw new IllegalArgumentException("Negative timeouts not permitted");
100        }
101    }
102
103    /**
104     * Wait up to |timeoutMs| (or until underlying socket error) for a
105     * netlink message of at most |bufsize| size.
106     *
107     * Multi-threaded calls with different timeouts will cause unexpected results.
108     */
109    public ByteBuffer recvMessage(int bufsize, long timeoutMs)
110            throws ErrnoException, IllegalArgumentException, InterruptedIOException {
111        checkTimeout(timeoutMs);
112
113        synchronized (mDescriptor) {
114            if (mLastRecvTimeoutMs != timeoutMs) {
115                Os.setsockoptTimeval(mDescriptor,
116                        OsConstants.SOL_SOCKET, OsConstants.SO_RCVTIMEO,
117                        StructTimeval.fromMillis(timeoutMs));
118                mLastRecvTimeoutMs = timeoutMs;
119            }
120        }
121
122        ByteBuffer byteBuffer = ByteBuffer.allocate(bufsize);
123        int length = Os.read(mDescriptor, byteBuffer);
124        if (length == bufsize) {
125            Log.w(TAG, "maximum read");
126        }
127        byteBuffer.position(0);
128        byteBuffer.limit(length);
129        byteBuffer.order(ByteOrder.nativeOrder());
130        return byteBuffer;
131    }
132
133    /**
134     * Send a message to a peer to which this socket has previously connected.
135     *
136     * This blocks until completion or an error occurs.
137     */
138    public boolean sendMessage(byte[] bytes, int offset, int count)
139            throws ErrnoException, InterruptedIOException {
140        return sendMessage(bytes, offset, count, 0);
141    }
142
143    /**
144     * Send a message to a peer to which this socket has previously connected,
145     * waiting at most |timeoutMs| milliseconds for the send to complete.
146     *
147     * Multi-threaded calls with different timeouts will cause unexpected results.
148     */
149    public boolean sendMessage(byte[] bytes, int offset, int count, long timeoutMs)
150            throws ErrnoException, IllegalArgumentException, InterruptedIOException {
151        checkTimeout(timeoutMs);
152
153        synchronized (mDescriptor) {
154            if (mLastSendTimeoutMs != timeoutMs) {
155                Os.setsockoptTimeval(mDescriptor,
156                        OsConstants.SOL_SOCKET, OsConstants.SO_SNDTIMEO,
157                        StructTimeval.fromMillis(timeoutMs));
158                mLastSendTimeoutMs = timeoutMs;
159            }
160        }
161
162        return (count == Os.write(mDescriptor, bytes, offset, count));
163    }
164
165    @Override
166    public void close() {
167        IoUtils.closeQuietly(mDescriptor);
168    }
169}
170