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.system;
18
19import java.net.SocketAddress;
20import java.nio.charset.StandardCharsets;
21import java.util.Arrays;
22
23/**
24 * A UNIX-domain (AF_UNIX / AF_LOCAL) socket address.
25 *
26 * @hide
27 */
28public final class UnixSocketAddress extends SocketAddress {
29
30    private static final int NAMED_PATH_LENGTH = OsConstants.UNIX_PATH_MAX;
31    private static final byte[] UNNAMED_PATH = new byte[0];
32
33    // See unix(7): Three types of UnixSocketAddress:
34    // 1) pathname: 0 < sun_path.length <= NAMED_PATH_LENGTH, sun_path[0] != 0.
35    // 2) unnamed: sun_path = [].
36    // 3) abstract: 0 < sun_path.length <= NAMED_PATH_LENGTH, sun_path[0] == 0.
37    private byte[] sun_path;
38
39    /** This constructor is also used from JNI. */
40    private UnixSocketAddress(byte[] sun_path) {
41        if (sun_path == null) {
42            throw new IllegalArgumentException("sun_path must not be null");
43        }
44        if (sun_path.length > NAMED_PATH_LENGTH) {
45            throw new IllegalArgumentException("sun_path exceeds the maximum length");
46        }
47
48        if (sun_path.length == 0) {
49            this.sun_path = UNNAMED_PATH;
50        } else {
51            this.sun_path = new byte[sun_path.length];
52            System.arraycopy(sun_path, 0, this.sun_path, 0, sun_path.length);
53        }
54    }
55
56    /**
57     * Creates a named, abstract AF_UNIX socket address.
58     */
59    public static UnixSocketAddress createAbstract(String name) {
60        byte[] nameBytes = name.getBytes(StandardCharsets.UTF_8);
61        // Abstract sockets have a path that starts with (byte) 0.
62        byte[] path = new byte[nameBytes.length + 1];
63        System.arraycopy(nameBytes, 0, path, 1, nameBytes.length);
64        return new UnixSocketAddress(path);
65    }
66
67    /**
68     * Creates a named, filesystem AF_UNIX socket address.
69     */
70    public static UnixSocketAddress createFileSystem(String pathName) {
71        byte[] pathNameBytes = pathName.getBytes(StandardCharsets.UTF_8);
72        // File system sockets have a path that ends with (byte) 0.
73        byte[] path = new byte[pathNameBytes.length + 1];
74        System.arraycopy(pathNameBytes, 0, path, 0, pathNameBytes.length);
75        return new UnixSocketAddress(path);
76    }
77
78    /**
79     * Creates an unnamed, filesystem AF_UNIX socket address.
80     */
81    public static UnixSocketAddress createUnnamed() {
82        return new UnixSocketAddress(UNNAMED_PATH);
83    }
84
85    /** Used for testing. */
86    public byte[] getSunPath() {
87        if (sun_path.length == 0) {
88            return sun_path;
89        }
90        byte[] sunPathCopy = new byte[sun_path.length];
91        System.arraycopy(sun_path, 0, sunPathCopy, 0, sun_path.length);
92        return sunPathCopy;
93    }
94
95    @Override
96    public boolean equals(Object o) {
97        if (this == o) {
98            return true;
99        }
100        if (o == null || getClass() != o.getClass()) {
101            return false;
102        }
103
104        UnixSocketAddress that = (UnixSocketAddress) o;
105        return Arrays.equals(sun_path, that.sun_path);
106    }
107
108    @Override
109    public int hashCode() {
110        return Arrays.hashCode(sun_path);
111    }
112
113    @Override
114    public String toString() {
115        return "UnixSocketAddress[" +
116                "sun_path=" + Arrays.toString(sun_path) +
117                ']';
118    }
119}
120