1 /* InetAddress.java -- Class to model an Internet address
2 Copyright (C) 1998, 1999, 2002, 2004, 2005 Free Software Foundation, Inc.
4 This file is part of GNU Classpath.
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING. If not, write to the
18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library. Thus, the terms and
23 conditions of the GNU General Public License cover the whole
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module. An independent module is a module which is not derived from
33 or based on this library. If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so. If you do not wish to do so, delete this
36 exception statement from your version. */
41 import gnu.classpath.Configuration;
43 import java.io.IOException;
44 import java.io.ObjectInputStream;
45 import java.io.ObjectOutputStream;
46 import java.io.ObjectStreamException;
47 import java.io.Serializable;
50 * This class models an Internet address. It does not have a public
51 * constructor. Instead, new instances of this objects are created
52 * using the static methods getLocalHost(), getByName(), and
55 * <p>This class fulfills the function of the C style functions gethostname(),
56 * gethostbyname(), and gethostbyaddr(). It resolves Internet DNS names
57 * into their corresponding numeric addresses and vice versa.</p>
59 * @author Aaron M. Renn (arenn@urbanophile.com)
62 * @specnote This class is not final since JK 1.4
64 public class InetAddress implements Serializable
66 private static final long serialVersionUID = 3286316764910316507L;
69 * Dummy InetAddress, used to bind socket to any (all) network interfaces.
71 static InetAddress ANY_IF;
73 private static final byte[] loopbackAddress = { 127, 0, 0, 1 };
75 private static final InetAddress loopback
76 = new Inet4Address(loopbackAddress, "localhost");
78 private static InetAddress localhost = null;
82 // load the shared library needed for name resolution
83 if (Configuration.INIT_LOAD_LIBRARY)
84 System.loadLibrary("javanet");
86 byte[] zeros = { 0, 0, 0, 0 };
87 ANY_IF = new Inet4Address(zeros, "0.0.0.0");
91 * The Serialized Form specifies that an int 'address' is saved/restored.
92 * This class uses a byte array internally so we'll just do the conversion
93 * at serialization time and leave the rest of the algorithm as is.
98 * An array of octets representing an IP address.
100 transient byte[] addr;
103 * The name of the host for this address.
108 * The field 'family' seems to be the AF_ value.
109 * FIXME: Much of the code in the other java.net classes does not make
110 * use of this family field. A better implementation would be to make
111 * use of getaddrinfo() and have other methods just check the family
112 * field rather than examining the length of the address each time.
117 * Initializes this object's addr instance variable from the passed in
118 * byte array. Note that this constructor is protected and is called
119 * only by static methods in this class.
121 * @param ipaddr The IP number of this address as an array of bytes
122 * @param hostname The hostname of this IP address.
124 InetAddress(byte[] ipaddr, String hostname)
126 addr = (null == ipaddr) ? null : (byte[]) ipaddr.clone();
130 family = getFamily(ipaddr);
134 * Returns true if this address is a multicast address, false otherwise.
135 * An address is multicast if the high four bits are "1110". These are
136 * also known as "Class D" addresses.
138 * @return true if mulitcast, false if not
142 public boolean isMulticastAddress()
144 // Mask against high order bits of 1110
145 if (addr.length == 4)
146 return (addr[0] & 0xF0) == 0xE0;
148 // Mask against high order bits of 11111111
149 if (addr.length == 16)
150 return addr [0] == (byte) 0xFF;
156 * Utility routine to check if the InetAddress in a wildcard address
160 public boolean isAnyLocalAddress()
162 // This is the IPv4 implementation.
163 // Any class derived from InetAddress should override this.
164 return equals(ANY_IF);
168 * Utility routine to check if the InetAddress is a loopback address
172 public boolean isLoopbackAddress()
174 // This is the IPv4 implementation.
175 // Any class derived from InetAddress should override this.
176 return addr[0] == 0x7F;
180 * Utility routine to check if InetAddress is a link local address
184 public boolean isLinkLocalAddress()
186 // This is the IPv4 implementation.
187 // Any class derived from InetAddress should override this.
188 // XXX: This seems to not exist with IPv4 addresses
193 * Utility routine to check if InetAddress is a site local address
197 public boolean isSiteLocalAddress()
199 // This is the IPv4 implementation.
200 // Any class derived from InetAddress should override this.
205 // XXX: Suns JDK 1.4.1 (on Linux) seems to have a bug here:
206 // it says 172.16.0.0 - 172.255.255.255 are site local addresses
208 if (addr[0] == 0xAC && (addr[1] & 0xF0) == 0x01)
212 if (addr[0] == 0xC0 && addr[1] == 0xA8)
215 // XXX: Do we need to check more addresses here ?
220 * Utility routine to check if InetAddress is a global multicast address
224 public boolean isMCGlobal()
226 // This is the IPv4 implementation.
227 // Any class derived from InetAddress should override this.
228 // XXX: This seems to not exist with IPv4 addresses
233 * Utility routine to check if InetAddress is a node local multicast address.
237 public boolean isMCNodeLocal()
239 // This is the IPv4 implementation.
240 // Any class derived from InetAddress should override this.
241 // XXX: This seems to not exist with IPv4 addresses
246 * Utility routine to check if InetAddress is a link local multicast address.
250 public boolean isMCLinkLocal()
252 // This is the IPv4 implementation.
253 // Any class derived from InetAddress should override this.
254 if (! isMulticastAddress())
257 return (addr[0] == 0xE0 && addr[1] == 0x00 && addr[2] == 0x00);
261 * Utility routine to check if InetAddress is a site local multicast address.
265 public boolean isMCSiteLocal()
267 // This is the IPv4 implementation.
268 // Any class derived from InetAddress should override this.
269 // XXX: This seems to not exist with IPv4 addresses
274 * Utility routine to check if InetAddress is a organization local
279 public boolean isMCOrgLocal()
281 // This is the IPv4 implementation.
282 // Any class derived from InetAddress should override this.
283 // XXX: This seems to not exist with IPv4 addresses
288 * Returns the hostname for this address. This will return the IP address
289 * as a String if there is no hostname available for this address
291 * @return The hostname for this address
293 public String getHostName()
295 if (hostName != null)
298 // Lookup hostname and set field.
299 lookup (null, this, false);
305 * Returns the canonical hostname represented by this InetAddress
309 public String getCanonicalHostName()
311 SecurityManager sm = System.getSecurityManager();
316 sm.checkConnect(hostName, -1);
318 catch (SecurityException e)
320 return getHostAddress();
324 // Try to find the FDQN now
326 byte[] ipaddr = getAddress();
328 if (ipaddr.length == 16)
329 address = new Inet6Address(getAddress(), null);
331 address = new Inet4Address(getAddress(), null);
333 return address.getHostName();
337 * Returns the IP address of this object as a byte array.
341 public byte[] getAddress()
343 // An experiment shows that JDK1.2 returns a different byte array each
344 // time. This makes sense, in terms of security.
345 return (byte[]) addr.clone();
348 /* Helper function due to a CNI limitation. */
349 private static InetAddress[] allocArray (int count)
351 return new InetAddress [count];
354 /* Helper function due to a CNI limitation. */
355 private static SecurityException checkConnect (String hostname)
357 SecurityManager s = System.getSecurityManager();
364 s.checkConnect (hostname, -1);
367 catch (SecurityException ex)
374 * Returns the IP address of this object as a String. The address is in
375 * the dotted octet notation, for example, "127.0.0.1".
377 * @return The IP address of this object in String form
381 public String getHostAddress()
383 StringBuffer sb = new StringBuffer(40);
385 int len = addr.length;
389 { // An IPv6 address.
393 return sb.toString();
395 int x = ((addr [i] & 0xFF) << 8) | (addr [i + 1] & 0xFF);
396 boolean empty = sb.length() == 0;
400 if (i == 10 && x == 0xFFFF)
401 { // IPv4-mapped IPv6 address.
402 sb.append (":FFFF:");
403 break; // Continue as IPv4 address;
406 { // IPv4-compatible IPv6 address.
408 break; // Continue as IPv4 address.
416 if (x != 0 || i >= 14)
417 sb.append (Integer.toHexString (x).toUpperCase());
423 sb.append(addr[i] & 0xff);
432 return sb.toString();
436 * Returns a hash value for this address. Useful for creating hash
437 * tables. Overrides Object.hashCode()
439 * @return A hash value for this address.
441 public int hashCode()
443 // There hashing algorithm is not specified, but a simple experiment
444 // shows that it is equal to the address, as a 32-bit big-endian integer.
446 int len = addr.length;
447 int i = len > 4 ? len - 4 : 0;
450 hash = (hash << 8) | (addr[i] & 0xFF);
456 * Tests this address for equality against another InetAddress. The two
457 * addresses are considered equal if they contain the exact same octets.
458 * This implementation overrides Object.equals()
460 * @param obj The address to test for equality
462 * @return true if the passed in object's address is equal to this one's,
465 public boolean equals(Object obj)
467 if (! (obj instanceof InetAddress))
470 // "The Java Class Libraries" 2nd edition says "If a machine has
471 // multiple names instances of InetAddress for different name of
472 // that same machine are not equal. This is because they have
473 // different host names." This violates the description in the
474 // JDK 1.2 API documentation. A little experimentation
475 // shows that the latter is correct.
476 byte[] addr2 = ((InetAddress) obj).addr;
478 if (addr.length != addr2.length)
481 for (int i = 0; i < addr.length; i++)
482 if (addr[i] != addr2[i])
489 * Converts this address to a String. This string contains the IP in
490 * dotted decimal form. For example: "127.0.0.1" This method is equivalent
491 * to getHostAddress() and overrides Object.toString()
493 * @return This address in String form
495 public String toString()
497 String addr = getHostAddress();
498 String host = (hostName != null) ? hostName : addr;
499 return host + "/" + addr;
503 * Returns an InetAddress object given the raw IP address.
505 * The argument is in network byte order: the highest order byte of the
506 * address is in getAddress()[0].
508 * @param addr The IP address to create the InetAddress object from
510 * @exception UnknownHostException If IP address has illegal length
514 public static InetAddress getByAddress(byte[] addr)
515 throws UnknownHostException
517 return getByAddress(null, addr);
521 * Creates an InetAddress based on the provided host name and IP address.
522 * No name service is checked for the validity of the address.
524 * @param host The hostname of the InetAddress object to create
525 * @param addr The IP address to create the InetAddress object from
527 * @exception UnknownHostException If IP address is of illegal length
531 public static InetAddress getByAddress(String host, byte[] addr)
532 throws UnknownHostException
534 if (addr.length == 4)
535 return new Inet4Address(addr, host);
537 if (addr.length == 16)
538 return new Inet6Address(addr, host);
540 throw new UnknownHostException("IP address has illegal length");
544 * If hostname is a valid numeric IP address, return the numeric address.
545 * Otherwise, return null.
547 * @param hostname the name of the host
549 private static native byte[] aton(String hostname);
552 * Looks up all addresses of a given host.
554 * @param hostname the host to lookup
555 * @param ipaddr FIXME
558 * @return an array with all found addresses
560 private static native InetAddress[] lookup (String hostname,
561 InetAddress ipaddr, boolean all);
564 * Returns tha family type of an IP address.
566 * @param addr the IP address
570 private static native int getFamily (byte[] ipaddr);
573 * Returns an InetAddress object representing the IP address of the given
574 * hostname. This name can be either a hostname such as "www.urbanophile.com"
575 * or an IP address in dotted decimal format such as "127.0.0.1". If the
576 * hostname is null or "", the hostname of the local machine is supplied by
577 * default. This method is equivalent to returning the first element in
578 * the InetAddress array returned from GetAllByName.
580 * @param hostname The name of the desired host, or null for the local
583 * @return The address of the host as an InetAddress object.
585 * @exception UnknownHostException If no IP address for the host could
587 * @exception SecurityException If a security manager exists and its
588 * checkConnect method doesn't allow the operation
590 public static InetAddress getByName(String hostname)
591 throws UnknownHostException
593 // If null or the empty string is supplied, the loopback address
594 // is returned. Note that this is permitted without a security check.
595 if (hostname == null || hostname.length() == 0)
598 SecurityManager s = System.getSecurityManager();
600 s.checkConnect(hostname, -1);
602 // Assume that the host string is an IP address
603 byte[] address = aton(hostname);
606 if (address.length == 4)
607 return new Inet4Address (address, null);
608 else if (address.length == 16)
610 if ((address [10] == 0xFF) && (address [11] == 0xFF))
612 byte[] ip4addr = new byte [4];
613 ip4addr [0] = address [12];
614 ip4addr [1] = address [13];
615 ip4addr [2] = address [14];
616 ip4addr [3] = address [15];
617 return new Inet4Address (ip4addr, null);
619 return new Inet6Address (address, null);
622 throw new UnknownHostException ("Address has invalid length");
625 // Try to resolve the host by DNS
626 InetAddress result = new InetAddress(null, null);
627 lookup (hostname, result, false);
632 * Returns an array of InetAddress objects representing all the host/ip
633 * addresses of a given host, given the host's name. This name can be
634 * either a hostname such as "www.urbanophile.com" or an IP address in
635 * dotted decimal format such as "127.0.0.1". If the value is null, the
636 * hostname of the local machine is supplied by default.
638 * @param hostname The name of the desired host, or null for the
639 * local loopback address.
641 * @return All addresses of the host as an array of InetAddress objects.
643 * @exception UnknownHostException If no IP address for the host could
645 * @exception SecurityException If a security manager exists and its
646 * checkConnect method doesn't allow the operation
648 public static InetAddress[] getAllByName(String hostname)
649 throws UnknownHostException
651 // If null or the empty string is supplied, the loopback address
652 // is returned. Note that this is permitted without a security check.
653 if (hostname == null || hostname.length() == 0)
654 return new InetAddress[] {loopback};
656 SecurityManager s = System.getSecurityManager();
658 s.checkConnect(hostname, -1);
660 // Check if hostname is an IP address
661 byte[] address = aton (hostname);
664 InetAddress[] result = new InetAddress [1];
665 result [0] = new InetAddress (address, null);
669 // Try to resolve the hostname by DNS
670 return lookup (hostname, null, true);
674 * This native method looks up the hostname of the local machine
675 * we are on. If the actual hostname cannot be determined, then the
676 * value "localhost" will be used. This native method wrappers the
677 * "gethostname" function.
679 * @return The local hostname.
681 private static native String getLocalHostname();
684 * Returns an InetAddress object representing the address of the current
687 * @return The local host's address
689 * @exception UnknownHostException If no IP address for the host could
692 public static InetAddress getLocalHost() throws UnknownHostException
694 SecurityManager s = System.getSecurityManager();
696 // Experimentation shows that JDK1.2 does cache the result.
697 // However, if there is a security manager, and the cached result
698 // is other than "localhost", we need to check again.
699 if (localhost == null
700 || (s != null && ! localhost.isLoopbackAddress()))
706 private static synchronized void getLocalHost (SecurityManager s)
707 throws UnknownHostException
709 // Check the localhost cache again, now that we've synchronized.
710 if (s == null && localhost != null)
713 String hostname = getLocalHostname();
717 // "The Java Class Libraries" suggests that if the security
718 // manager disallows getting the local host name, then
719 // we use the loopback host.
720 // However, the JDK 1.2 API claims to throw SecurityException,
721 // which seems to suggest SecurityException is *not* caught.
722 // In this case, experimentation shows that former is correct.
725 // This is wrong, if the name returned from getLocalHostname()
726 // is not a fully qualified name. FIXME.
727 s.checkConnect (hostname, -1);
729 catch (SecurityException ex)
735 if (hostname != null && hostname.length() != 0)
739 localhost = new InetAddress (null, null);
740 lookup (hostname, localhost, false);
747 throw new UnknownHostException();
749 if (localhost == null)
750 localhost = new InetAddress (loopbackAddress, "localhost");
754 * Needed for serialization
756 private void readResolve() throws ObjectStreamException
758 // FIXME: implement this
761 private void readObject(ObjectInputStream ois)
762 throws IOException, ClassNotFoundException
764 ois.defaultReadObject();
766 addr[3] = (byte) address;
768 for (int i = 2; i >= 0; --i)
769 addr[i] = (byte) (address >>= 8);
771 // Ignore family from serialized data. Since the saved address is 32 bits
772 // the deserialized object will have an IPv4 address i.e. AF_INET family.
773 // FIXME: An alternative is to call the aton method on the deserialized
774 // hostname to get a new address. The Serialized Form doc is silent
775 // on how these fields are used.
776 family = getFamily (addr);
779 private void writeObject(ObjectOutputStream oos) throws IOException
781 // Build a 32 bit address from the last 4 bytes of a 4 byte IPv4 address
782 // or a 16 byte IPv6 address.
783 int len = addr.length;
787 address = address << 8 | (((int) addr[i]) & 0xFF);
789 oos.defaultWriteObject();