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      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 
     17 package android.system;
     18 
     19 import java.net.SocketAddress;
     20 import java.nio.charset.StandardCharsets;
     21 import java.util.Arrays;
     22 
     23 /**
     24  * A UNIX-domain (AF_UNIX / AF_LOCAL) socket address.
     25  *
     26  * @hide
     27  */
     28 public 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