1 /*
 2  * Copyright (c) 2002, 2021, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.  Oracle designates this
 8  * particular file as subject to the "Classpath" exception as provided
 9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 package java.net;
26 import java.io.IOException;
27 import java.net.spi.InetAddressResolver.LookupPolicy;
28 
29 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV4;
30 
31 /*
32  * Package private implementation of InetAddressImpl for IPv4.
33  *
34  * @since 1.4
35  */
36 final class Inet4AddressImpl implements InetAddressImpl {
37     public native String getLocalHostName() throws UnknownHostException;
38     public InetAddress[] lookupAllHostAddr(String hostname, LookupPolicy lookupPolicy)
39             throws UnknownHostException {
40         if ((lookupPolicy.characteristics() & IPV4) == 0) {
41             throw new UnknownHostException(hostname);
42         }
43         return lookupAllHostAddr(hostname);
44     }
45     private native InetAddress[] lookupAllHostAddr(String hostname) throws UnknownHostException;
46     public native String getHostByAddr(byte[] addr) throws UnknownHostException;
47     private native boolean isReachable0(byte[] addr, int timeout, byte[] ifaddr, int ttl) throws IOException;
48 
49     public synchronized InetAddress anyLocalAddress() {
50         if (anyLocalAddress == null) {
51             anyLocalAddress = new Inet4Address(); // {0x00,0x00,0x00,0x00}
52             anyLocalAddress.holder().hostName = "0.0.0.0";
53         }
54         return anyLocalAddress;
55     }
56 
57     public synchronized InetAddress loopbackAddress() {
58         if (loopbackAddress == null) {
59             byte[] loopback = {0x7f,0x00,0x00,0x01};
60             loopbackAddress = new Inet4Address("localhost", loopback);
61         }
62         return loopbackAddress;
63     }
64 
65   public boolean isReachable(InetAddress addr, int timeout, NetworkInterface netif, int ttl) throws IOException {
66       byte[] ifaddr = null;
67       if (netif != null) {
68           /*
69            * Let's make sure we use an address of the proper family
70            */
71           java.util.Enumeration<InetAddress> it = netif.getInetAddresses();
72           InetAddress inetaddr = null;
73           while (!(inetaddr instanceof Inet4Address) &&
74                  it.hasMoreElements())
75               inetaddr = it.nextElement();
76           if (inetaddr instanceof Inet4Address)
77               ifaddr = inetaddr.getAddress();
78       }
79       return isReachable0(addr.getAddress(), timeout, ifaddr, ttl);
80   }
81     private InetAddress      anyLocalAddress;
82     private InetAddress      loopbackAddress;
83 }
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