cc40c1e130
* java/net/InetAddress.java: (isMulticastAddress): Added documentation. (getHostAddress): Added documentation. (toString): Added documentation. (getByAddress): Fixed documentation. (getByName): Added documentation. (getAllByName): Added documentation. (getLocalHost): Added documentation. From-SVN: r57814
365 lines
10 KiB
Java
365 lines
10 KiB
Java
// INetAddress.java -- An Internet Protocol (IP) address.
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/* Copyright (C) 1998, 1999, 2000 Free Software Foundation
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This file is part of libgcj.
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This software is copyrighted work licensed under the terms of the
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Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
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details. */
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package java.net;
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import java.io.ObjectInputStream;
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import java.io.ObjectOutputStream;
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import java.io.IOException;
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import java.io.Serializable;
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/**
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* @author Per Bothner
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* @date January 6, 1999.
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*/
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/*
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* Written using on-line Java Platform 1.2 API Specification, as well
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* as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
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* (The latter turns out to have some errors ...)
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* Status: Believed complete and correct.
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*
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* @specnote This class is not final since JK 1.4
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*/
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public class InetAddress implements Serializable
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{
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// The Serialized Form specifies that an int 'address' is saved/restored.
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// This class uses a byte array internally so we'll just do the conversion
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// at serialization time and leave the rest of the algorithm as is.
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private int address;
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transient byte[] addr;
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String hostName;
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// The field 'family' seems to be the AF_ value.
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// FIXME: Much of the code in the other java.net classes does not make
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// use of this family field. A better implementation would be to make
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// use of getaddrinfo() and have other methods just check the family
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// field rather than examining the length of the address each time.
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int family;
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private static final long serialVersionUID = 3286316764910316507L;
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private void readObject(ObjectInputStream ois)
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throws IOException, ClassNotFoundException
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{
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ois.defaultReadObject();
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addr = new byte[4];
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addr[3] = (byte) address;
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for (int i = 2; i >= 0; --i)
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addr[i] = (byte) (address >>= 8);
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// Ignore family from serialized data. Since the saved address is 32 bits
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// the deserialized object will have an IPv4 address i.e. AF_INET family.
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// FIXME: An alternative is to call the aton method on the deserialized
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// hostname to get a new address. The Serialized Form doc is silent
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// on how these fields are used.
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family = getFamily (addr);
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}
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private void writeObject(ObjectOutputStream oos) throws IOException
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{
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// Build a 32 bit address from the last 4 bytes of a 4 byte IPv4 address
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// or a 16 byte IPv6 address.
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int len = addr.length;
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int i = len - 4;
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for (; i < len; i++)
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address = address << 8 | (((int) addr[i]) & 0xFF);
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oos.defaultWriteObject();
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}
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private static native int getFamily (byte[] address);
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InetAddress (byte[] address, String hostname)
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{
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addr = address;
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hostName = hostname;
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if (address != null)
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family = getFamily (address);
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}
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/**
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* Utility routine to check if the InetAddress is an IP multicast address
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*
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* @since 1.1
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*/
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public boolean isMulticastAddress ()
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{
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int len = addr.length;
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if (len == 4)
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return (addr[0] & 0xF0) == 0xE0;
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if (len == 16)
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return addr[0] == (byte) 0xFF;
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return false;
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}
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public String getHostName ()
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{
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if (hostName == null)
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lookup (null, this, false);
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return hostName;
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}
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public byte[] getAddress ()
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{
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// An experiment shows that JDK1.2 returns a different byte array each
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// time. This makes sense, in terms of security.
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return (byte[]) addr.clone();
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}
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/* Helper function due to a CNI limitation. */
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private static InetAddress[] allocArray (int count)
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{
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return new InetAddress[count];
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}
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/* Helper function due to a CNI limitation. */
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private static SecurityException checkConnect (String hostname)
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{
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SecurityManager s = System.getSecurityManager();
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if (s == null)
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return null;
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try
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{
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s.checkConnect(hostname, -1);
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return null;
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}
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catch (SecurityException ex)
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{
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return ex;
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}
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}
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/**
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* Returns the IP address as string
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*
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* @since 1.0.2
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*/
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public String getHostAddress ()
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{
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StringBuffer sbuf = new StringBuffer(40);
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int len = addr.length;
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int i = 0;
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if (len == 16)
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{ // An IPv6 address.
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for (; ; i += 2)
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{
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if (i >= 16)
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return sbuf.toString();
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int x = ((addr[i] & 0xFF) << 8) | (addr[i+1] & 0xFF);
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boolean empty = sbuf.length() == 0;
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if (empty)
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{
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if (i == 10 && x == 0xFFFF)
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{ // IPv4-mapped IPv6 address.
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sbuf.append(":FFFF:");
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break; // Continue as IPv4 address;
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}
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else if (i == 12)
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{ // IPv4-compatible IPv6 address.
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sbuf.append(':');
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break; // Continue as IPv4 address.
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}
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else if (i > 0)
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sbuf.append("::");
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}
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else
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sbuf.append(':');
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if (x != 0 || i >= 14)
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sbuf.append(Integer.toHexString(x).toUpperCase());
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}
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}
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for ( ; ; )
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{
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sbuf.append(addr[i] & 0xFF);
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i++;
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if (i == len)
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break;
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sbuf.append('.');
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}
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return sbuf.toString();
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}
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public int hashCode()
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{
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// There hashing algorithm is not specified, but a simple experiment
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// shows that it is equal to the address, as a 32-bit big-endian integer.
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int hash = 0;
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int len = addr.length;
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int i = len > 4 ? len - 4 : 0;
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for ( ; i < len; i++)
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hash = (hash << 8) | (addr[i] & 0xFF);
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return hash;
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}
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public boolean equals (Object obj)
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{
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if (obj == null || ! (obj instanceof InetAddress))
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return false;
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// "The Java Class Libraries" 2nd edition says "If a machine has
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// multiple names instances of InetAddress for different name of
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// that same machine are not equal. This is because they have
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// different host names." This violates the description in the
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// JDK 1.2 API documentation. A little experimentation
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// shows that the latter is correct.
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byte[] addr1 = addr;
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byte[] addr2 = ((InetAddress) obj).addr;
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if (addr1.length != addr2.length)
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return false;
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for (int i = addr1.length; --i >= 0; )
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if (addr1[i] != addr2[i])
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return false;
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return true;
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}
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/**
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* Returns then <code>InetAddress</code> as string
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*/
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public String toString()
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{
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return getHostName()+'/'+getHostAddress();
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}
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/**
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* Returns an InetAddress object given the raw IP address.
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*
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* The argument is in network byte order: the highest order byte of the
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* address is in getAddress()[0].
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*
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* @exception UnknownHostException If IP address has illegal length
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* be found
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*
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* @since 1.4
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*/
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public static InetAddress getByAddress(byte[] addr)
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throws UnknownHostException
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{
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if (addr.length != 4 && addr.length != 16)
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throw new UnknownHostException ("IP address has illegal length");
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return new InetAddress (addr, "");
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}
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/** If host is a valid numeric IP address, return the numeric address.
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* Otherwise, return null. */
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private static native byte[] aton (String host);
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private static native InetAddress[] lookup
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(String hostname, InetAddress addr, boolean all);
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/**
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* Determines the IP address of a host, given the host's name.
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*
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* @exception UnknownHostException If no IP address for the host could
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* be found
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* @exception SecurityException If a security manager exists and its
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* checkConnect method doesn't allow the operation
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*/
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public static InetAddress getByName (String host)
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throws UnknownHostException
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{
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if (host == null)
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return getLocalHost();
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byte[] address = aton(host);
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if (address != null)
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return new InetAddress(address, null);
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InetAddress iaddr = new InetAddress(null, host);
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lookup(host, iaddr, false);
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return iaddr;
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}
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/**
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* Given the name of a host, returns an array of its IP addresses,
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* based on the configured name service on the system.
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*
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* @exception UnknownHostException If no IP address for the host could
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* be found
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* @exception SecurityException If a security manager exists and its
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* checkConnect method doesn't allow the operation
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*/
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public static InetAddress[] getAllByName (String host)
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throws UnknownHostException
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{
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byte[] address = aton(host);
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if (address != null)
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{
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InetAddress[] result = new InetAddress[1];
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result[0] = new InetAddress(address, null);
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return result;
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}
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return lookup(host, null, true);
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}
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static final byte[] zeros = {0,0,0,0};
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/* dummy InetAddress, used to bind socket to any (all) network interfaces */
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static final InetAddress ANY_IF = new InetAddress(zeros, null);
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private static final byte[] localhostAddress = { 127, 0, 0, 1 };
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private static native String getLocalHostname ();
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private static InetAddress localhost = null;
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/**
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* Returns the local host
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*
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* @exception UnknownHostException If no IP address for the host could
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* be found
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*/
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public static InetAddress getLocalHost() throws UnknownHostException
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{
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SecurityManager s = System.getSecurityManager();
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// Experimentation shows that JDK1.2 does cache the result.
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// However, if there is a security manager, and the cached result
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// is other than "localhost", we need to check again.
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if (localhost == null
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|| (s != null && localhost.addr != localhostAddress))
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getLocalHost(s);
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return localhost;
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}
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private static synchronized void getLocalHost(SecurityManager s)
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throws UnknownHostException
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{
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// Check the localhost cache again, now that we've synchronized.
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if (s == null && localhost != null)
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return;
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String hostname = getLocalHostname();
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if (s != null)
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{
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// "The Java Class Libraries" suggests that if the security
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// manager disallows getting the local host name, then
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// we use the loopback host.
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// However, the JDK 1.2 API claims to throw SecurityException,
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// which seems to suggest SecurityException is *not* caught.
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// In this case, experimentation shows that former is correct.
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try
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{
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// This is wrong, if the name returned from getLocalHostname()
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// is not a fully qualified name. FIXME.
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s.checkConnect(hostname, -1);
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}
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catch (SecurityException ex)
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{
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hostname = null;
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}
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}
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if (hostname != null)
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{
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try
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{
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localhost = new InetAddress(null, null);
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lookup(hostname, localhost, false);
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}
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catch (Exception ex)
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{
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}
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}
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if (localhost == null)
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localhost = new InetAddress (localhostAddress, "localhost");
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}
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}
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