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Inet6Address.javaAPI DocJava SE 6 API25626Tue Jun 10 00:25:40 BST 2008java.net

Inet6Address

public final class Inet6Address extends InetAddress
This class represents an Internet Protocol version 6 (IPv6) address. Defined by RFC 2373: IP Version 6 Addressing Architecture.

Textual representation of IP addresses

Textual representation of IPv6 address used as input to methods takes one of the following forms:
  1. The preferred form is x:x:x:x:x:x:x:x, where the 'x's are the hexadecimal values of the eight 16-bit pieces of the address. This is the full form. For example,

    1080:0:0:0:8:800:200C:417A

    Note that it is not necessary to write the leading zeros in an individual field. However, there must be at least one numeral in every field, except as described below.

  2. Due to some methods of allocating certain styles of IPv6 addresses, it will be common for addresses to contain long strings of zero bits. In order to make writing addresses containing zero bits easier, a special syntax is available to compress the zeros. The use of "::" indicates multiple groups of 16-bits of zeros. The "::" can only appear once in an address. The "::" can also be used to compress the leading and/or trailing zeros in an address. For example,

    1080::8:800:200C:417A
  3. An alternative form that is sometimes more convenient when dealing with a mixed environment of IPv4 and IPv6 nodes is x:x:x:x:x:x:d.d.d.d, where the 'x's are the hexadecimal values of the six high-order 16-bit pieces of the address, and the 'd's are the decimal values of the four low-order 8-bit pieces of the standard IPv4 representation address, for example,

    ::FFFF:129.144.52.38
    ::129.144.52.38

    where "::FFFF:d.d.d.d" and "::d.d.d.d" are, respectively, the general forms of an IPv4-mapped IPv6 address and an IPv4-compatible IPv6 address. Note that the IPv4 portion must be in the "d.d.d.d" form. The following forms are invalid:

    ::FFFF:d.d.d
    ::FFFF:d.d
    ::d.d.d
    ::d.d

    The following form:

    ::FFFF:d

    is valid, however it is an unconventional representation of the IPv4-compatible IPv6 address,

    ::255.255.0.d

    while "::d" corresponds to the general IPv6 address "0:0:0:0:0:0:0:d".

For methods that return a textual representation as output value, the full form is used. Inet6Address will return the full form because it is unambiguous when used in combination with other textual data.

Special IPv6 address

IPv4-mapped address Of the form::ffff:w.x.y.z, this IPv6 address is used to represent an IPv4 address. It allows the native program to use the same address data structure and also the same socket when communicating with both IPv4 and IPv6 nodes.

In InetAddress and Inet6Address, it is used for internal representation; it has no functional role. Java will never return an IPv4-mapped address. These classes can take an IPv4-mapped address as input, both in byte array and text representation. However, it will be converted into an IPv4 address.

Textual representation of IPv6 scoped addresses

The textual representation of IPv6 addresses as described above can be extended to specify IPv6 scoped addresses. This extension to the basic addressing architecture is described in [draft-ietf-ipngwg-scoping-arch-04.txt].

Because link-local and site-local addresses are non-global, it is possible that different hosts may have the same destination address and may be reachable through different interfaces on the same originating system. In this case, the originating system is said to be connected to multiple zones of the same scope. In order to disambiguate which is the intended destination zone, it is possible to append a zone identifier (or scope_id) to an IPv6 address.

The general format for specifying the scope_id is the following:

IPv6-address%scope_id

The IPv6-address is a literal IPv6 address as described above. The scope_id refers to an interface on the local system, and it can be specified in two ways.

  1. As a numeric identifier. This must be a positive integer that identifies the particular interface and scope as understood by the system. Usually, the numeric values can be determined through administration tools on the system. Each interface may have multiple values, one for each scope. If the scope is unspecified, then the default value used is zero.
  2. As a string. This must be the exact string that is returned by {@link java.net.NetworkInterface#getName()} for the particular interface in question. When an Inet6Address is created in this way, the numeric scope-id is determined at the time the object is created by querying the relevant NetworkInterface.

Note also, that the numeric scope_id can be retrieved from Inet6Address instances returned from the NetworkInterface class. This can be used to find out the current scope ids configured on the system.

since
1.4

Fields Summary
static final int
INADDRSZ
private transient int
cached_scope_id
byte[]
ipaddress
Holds a 128-bit (16 bytes) IPv6 address.
private int
scope_id
scope_id. The scope specified when the object is created. If the object is created with an interface name, then the scope_id is not determined until the time it is needed.
private boolean
scope_id_set
This will be set to true when the scope_id field contains a valid integer scope_id.
private transient NetworkInterface
scope_ifname
scoped interface. scope_id is derived from this as the scope_id of the first address whose scope is the same as this address for the named interface.
private boolean
scope_ifname_set
set if the object is constructed with a scoped interface instead of a numeric scope id.
private static final long
serialVersionUID
private static final int
INT16SZ
private String
ifname
Following field is only used during (de)/serialization
Constructors Summary
Inet6Address()


    /*
     * Perform initializations.
     */
     
        init();
    
	super();
	hostName = null;
	ipaddress = new byte[INADDRSZ];
	family = IPv6;
    
Inet6Address(String hostName, byte[] addr, int scope_id)

	this.hostName = hostName;
	if (addr.length == INADDRSZ) { // normal IPv6 address
	    family = IPv6;
	    ipaddress = (byte[])addr.clone();
	} 
	if (scope_id >= 0) {
	    this.scope_id = scope_id;
	    scope_id_set = true;
	}
    
Inet6Address(String hostName, byte[] addr)

	try {
	    initif (hostName, addr, null);
	} catch (UnknownHostException e) {} /* cant happen if ifname is null */
    
Inet6Address(String hostName, byte[] addr, NetworkInterface nif)

	initif (hostName, addr, nif);
    
Inet6Address(String hostName, byte[] addr, String ifname)

	initstr (hostName, addr, ifname);
    
Methods Summary
private intderiveNumericScope(java.net.NetworkInterface ifc)

	Enumeration addresses = ifc.getInetAddresses();
	while (addresses.hasMoreElements()) {
	    InetAddress address = (InetAddress)addresses.nextElement();
	    if (!(address instanceof Inet6Address)) {
		continue;	
	    }
	    Inet6Address ia6_addr = (Inet6Address)address;
	    /* check if site or link local prefixes match */
	    if (!differentLocalAddressTypes(ia6_addr)){
		/* type not the same, so carry on searching */
		continue;
	    }
	    /* found a matching address - return its scope_id */
	    return ia6_addr.scope_id;
	}
	throw new UnknownHostException ("no scope_id found");
    
private intderiveNumericScope(java.lang.String ifname)

	Enumeration en;
	try {
	    en = NetworkInterface.getNetworkInterfaces();
	} catch (SocketException e) {
	    throw new UnknownHostException ("could not enumerate local network interfaces");
	}
	while (en.hasMoreElements()) {
	    NetworkInterface ifc = (NetworkInterface)en.nextElement();
	    if (ifc.getName().equals (ifname)) {
		Enumeration addresses = ifc.getInetAddresses();
		while (addresses.hasMoreElements()) {
		    InetAddress address = (InetAddress)addresses.nextElement();
		    if (!(address instanceof Inet6Address)) {
			continue;	
		    }
		    Inet6Address ia6_addr = (Inet6Address)address;
		    /* check if site or link local prefixes match */
		    if (!differentLocalAddressTypes(ia6_addr)){
			/* type not the same, so carry on searching */
			continue;
		    }
		    /* found a matching address - return its scope_id */
		    return ia6_addr.scope_id;
		}
	    }
	}
	throw new UnknownHostException ("No matching address found for interface : " +ifname);
    
private booleandifferentLocalAddressTypes(java.net.Inet6Address other)


	if (isLinkLocalAddress() && !other.isLinkLocalAddress()) {
	    return false;
	}
	if (isSiteLocalAddress() && !other.isSiteLocalAddress()) {
	    return false;
	}
	return true;
    
public booleanequals(java.lang.Object obj)
Compares this object against the specified object. The result is true if and only if the argument is not null and it represents the same IP address as this object.

Two instances of InetAddress represent the same IP address if the length of the byte arrays returned by getAddress is the same for both, and each of the array components is the same for the byte arrays.

param
obj the object to compare against.
return
true if the objects are the same; false otherwise.
see
java.net.InetAddress#getAddress()

	if (obj == null || 
	    !(obj instanceof Inet6Address))
	    return false;

	Inet6Address inetAddr = (Inet6Address)obj;

	for (int i = 0; i < INADDRSZ; i++) {
	    if (ipaddress[i] != inetAddr.ipaddress[i])
		return false;
	}
	
	return true;
    
public byte[]getAddress()
Returns the raw IP address of this InetAddress object. The result is in network byte order: the highest order byte of the address is in getAddress()[0].

return
the raw IP address of this object.

	return (byte[])ipaddress.clone();
    
public static java.net.Inet6AddressgetByAddress(java.lang.String host, byte[] addr, java.net.NetworkInterface nif)
Create an Inet6Address in the exact manner of {@link InetAddress#getByAddress(String,byte[])} except that the IPv6 scope_id is set to the value corresponding to the given interface for the address type specified in addr. The call will fail with an UnknownHostException if the given interface does not have a numeric scope_id assigned for the given address type (eg. link-local or site-local). See here for a description of IPv6 scoped addresses.

param
host the specified host
param
addr the raw IP address in network byte order
param
nif an interface this address must be associated with.
return
an Inet6Address object created from the raw IP address.
exception
UnknownHostException if IP address is of illegal length, or if the interface does not have a numeric scope_id assigned for the given address type.
since
1.5

	if (host != null && host.length() > 0 && host.charAt(0) == '[") {
	    if (host.charAt(host.length()-1) == ']") {
		host = host.substring(1, host.length() -1);
	    }
	}
	if (addr != null) {
	    if (addr.length == Inet6Address.INADDRSZ) {
	    	return new Inet6Address(host, addr, nif); 
	    } 
	} 
	throw new UnknownHostException("addr is of illegal length");
    
public static java.net.Inet6AddressgetByAddress(java.lang.String host, byte[] addr, int scope_id)
Create an Inet6Address in the exact manner of {@link InetAddress#getByAddress(String,byte[])} except that the IPv6 scope_id is set to the given numeric value. The scope_id is not checked to determine if it corresponds to any interface on the system. See here for a description of IPv6 scoped addresses.

param
host the specified host
param
addr the raw IP address in network byte order
param
scope_id the numeric scope_id for the address.
return
an Inet6Address object created from the raw IP address.
exception
UnknownHostException if IP address is of illegal length.
since
1.5

	if (host != null && host.length() > 0 && host.charAt(0) == '[") {
	    if (host.charAt(host.length()-1) == ']") {
		host = host.substring(1, host.length() -1);
	    }
	}
	if (addr != null) {
	    if (addr.length == Inet6Address.INADDRSZ) {
	    	return new Inet6Address(host, addr, scope_id); 
	    } 
	} 
	throw new UnknownHostException("addr is of illegal length");
    
public java.lang.StringgetHostAddress()
Returns the IP address string in textual presentation. If the instance was created specifying a scope identifier then the scope id is appended to the IP address preceded by a "%" (per-cent) character. This can be either a numeric value or a string, depending on which was used to createthe instance.

return
the raw IP address in a string format.

	String s = numericToTextFormat(ipaddress);
	if (scope_ifname_set) { /* must check this first */
	    s = s + "%" + scope_ifname.getName();
	} else if (scope_id_set) {
	    s = s + "%" + scope_id;
	}
	return s;
    
public intgetScopeId()
Returns the numeric scopeId, if this instance is associated with an interface. If no scoped_id is set, the returned value is zero.

return
the scopeId, or zero if not set.
since
1.5

	return scope_id;
     
public java.net.NetworkInterfacegetScopedInterface()
Returns the scoped interface, if this instance was created with with a scoped interface.

return
the scoped interface, or null if not set.
since
1.5

	return scope_ifname;
     
public inthashCode()
Returns a hashcode for this IP address.

return
a hash code value for this IP address.

	if (ipaddress != null) {

	    int hash = 0;
	    int i=0;
  	    while (i<INADDRSZ) {
		int j=0;
		int component=0;
		while (j<4 && i<INADDRSZ) {
		    component = (component << 8) + ipaddress[i];
		    j++; 
		    i++;
		}
		hash += component;
	    }
	    return hash;

	} else {
	    return 0;
	}
    
private static native voidinit()
Perform class load-time initializations.

private voidinitif(java.lang.String hostName, byte[] addr, java.net.NetworkInterface nif)

	this.hostName = hostName;
	if (addr.length == INADDRSZ) { // normal IPv6 address
	    family = IPv6;
	    ipaddress = (byte[])addr.clone();
	} 
	if (nif != null) {
	    this.scope_ifname = nif;
	    scope_ifname_set = true;
	    scope_id = deriveNumericScope (nif);
	    scope_id_set = true;
	}
    
private voidinitstr(java.lang.String hostName, byte[] addr, java.lang.String ifname)

	try {
	    NetworkInterface nif = NetworkInterface.getByName (ifname);
	    if (nif == null) {
		throw new UnknownHostException ("no such interface " + ifname);
	    }
	    initif (hostName, addr, nif);
	} catch (SocketException e) {
	    throw new UnknownHostException ("SocketException thrown" + ifname);
	}
    
public booleanisAnyLocalAddress()
Utility routine to check if the InetAddress in a wildcard address.

return
a boolean indicating if the Inetaddress is a wildcard address.
since
1.4

	byte test = 0x00;
	for (int i = 0; i < INADDRSZ; i++) {
	    test |= ipaddress[i];
	}
	return (test == 0x00);
    
public booleanisIPv4CompatibleAddress()
Utility routine to check if the InetAddress is an IPv4 compatible IPv6 address.

return
a boolean indicating if the InetAddress is an IPv4 compatible IPv6 address; or false if address is IPv4 address.
since
1.4

	if ((ipaddress[0] == 0x00) && (ipaddress[1] == 0x00) && 
	    (ipaddress[2] == 0x00) && (ipaddress[3] == 0x00) && 
	    (ipaddress[4] == 0x00) && (ipaddress[5] == 0x00) && 
	    (ipaddress[6] == 0x00) && (ipaddress[7] == 0x00) && 
	    (ipaddress[8] == 0x00) && (ipaddress[9] == 0x00) && 
	    (ipaddress[10] == 0x00) && (ipaddress[11] == 0x00))  {   
	    return true;
	}
	return false;
    
public booleanisLinkLocalAddress()
Utility routine to check if the InetAddress is an link local address.

return
a boolean indicating if the InetAddress is a link local address; or false if address is not a link local unicast address.
since
1.4

	return ((ipaddress[0] & 0xff) == 0xfe 
		&& (ipaddress[1] & 0xc0) == 0x80);
    
public booleanisLoopbackAddress()
Utility routine to check if the InetAddress is a loopback address.

return
a boolean indicating if the InetAddress is a loopback address; or false otherwise.
since
1.4

	byte test = 0x00;
	for (int i = 0; i < 15; i++) {
	    test |= ipaddress[i];
	}
	return (test == 0x00) && (ipaddress[15] == 0x01);
    
public booleanisMCGlobal()
Utility routine to check if the multicast address has global scope.

return
a boolean indicating if the address has is a multicast address of global scope, false if it is not of global scope or it is not a multicast address
since
1.4

	return ((ipaddress[0] & 0xff) == 0xff
		&& (ipaddress[1] & 0x0f) == 0x0e);
    
public booleanisMCLinkLocal()
Utility routine to check if the multicast address has link scope.

return
a boolean indicating if the address has is a multicast address of link-local scope, false if it is not of link-local scope or it is not a multicast address
since
1.4

	return ((ipaddress[0] & 0xff) == 0xff
		&& (ipaddress[1] & 0x0f) == 0x02);
    
public booleanisMCNodeLocal()
Utility routine to check if the multicast address has node scope.

return
a boolean indicating if the address has is a multicast address of node-local scope, false if it is not of node-local scope or it is not a multicast address
since
1.4

	return ((ipaddress[0] & 0xff) == 0xff
		&& (ipaddress[1] & 0x0f) == 0x01);
    
public booleanisMCOrgLocal()
Utility routine to check if the multicast address has organization scope.

return
a boolean indicating if the address has is a multicast address of organization-local scope, false if it is not of organization-local scope or it is not a multicast address
since
1.4

	return ((ipaddress[0] & 0xff) == 0xff
		&& (ipaddress[1] & 0x0f) == 0x08);
    
public booleanisMCSiteLocal()
Utility routine to check if the multicast address has site scope.

return
a boolean indicating if the address has is a multicast address of site-local scope, false if it is not of site-local scope or it is not a multicast address
since
1.4

	return ((ipaddress[0] & 0xff) == 0xff
		&& (ipaddress[1] & 0x0f) == 0x05);
    
public booleanisMulticastAddress()
Utility routine to check if the InetAddress is an IP multicast address. 11111111 at the start of the address identifies the address as being a multicast address.

return
a boolean indicating if the InetAddress is an IP multicast address
since
JDK1.1

	return ((ipaddress[0] & 0xff) == 0xff);
    
public booleanisSiteLocalAddress()
Utility routine to check if the InetAddress is a site local address.

return
a boolean indicating if the InetAddress is a site local address; or false if address is not a site local unicast address.
since
1.4

	return ((ipaddress[0] & 0xff) == 0xfe 
		&& (ipaddress[1] & 0xc0) == 0xc0);
    
static java.lang.StringnumericToTextFormat(byte[] src)

    /*
     * Convert IPv6 binary address into presentation (printable) format.
     *
     * @param src a byte array representing the IPv6 numeric address
     * @return a String representing an IPv6 address in 
     *         textual representation format
     * @since 1.4
     */
       
    
	StringBuffer sb = new StringBuffer(39);
	for (int i = 0; i < (INADDRSZ / INT16SZ); i++) {
	    sb.append(Integer.toHexString(((src[i<<1]<<8) & 0xff00)
					  | (src[(i<<1)+1] & 0xff)));
	    if (i < (INADDRSZ / INT16SZ) -1 ) {
	       sb.append(":");
	    }
	}
	return sb.toString();
    
private voidreadObject(java.io.ObjectInputStream s)
restore the state of this object from stream including the scope information, only if the scoped interface name is valid on this system

	scope_ifname = null;
	scope_ifname_set = false;
	s.defaultReadObject();
	
	if (ifname != null && !"".equals (ifname)) {
	    try {
		scope_ifname = NetworkInterface.getByName(ifname);
		try {
		    scope_id = deriveNumericScope (scope_ifname);
		} catch (UnknownHostException e) {
		    // should not happen
		    assert false;
		}
	    } catch (SocketException e) {}

	    if (scope_ifname == null) {
	        /* the interface does not exist on this system, so we clear
 	         * the scope information completely */
	        scope_id_set = false;
	        scope_ifname_set = false;
	        scope_id = 0;
	    }
	}
	/* if ifname was not supplied, then the numeric info is used */
	    
	ipaddress = (byte[])ipaddress.clone();

	// Check that our invariants are satisfied
	if (ipaddress.length != INADDRSZ) {
	    throw new InvalidObjectException("invalid address length: "+
					     ipaddress.length);
	}
	
	if (family != IPv6) {
	    throw new InvalidObjectException("invalid address family type");
	}
    
private synchronized voidwriteObject(java.io.ObjectOutputStream s)
default behavior is overridden in order to write the scope_ifname field as a String, rather than a NetworkInterface which is not serializable

	if (scope_ifname_set) {
	    ifname = scope_ifname.getName();
	}
	s.defaultWriteObject();