Package org.xbill.DNS

Class ClientSubnetOption

java.lang.Object

org.xbill.DNS.EDNSOption

org.xbill.DNS.ClientSubnetOption

public class ClientSubnetOption
extends EDNSOption

The Client Subnet EDNS Option.

The option is used to convey information about the IP address of the originating client, so that an authoritative server can make decisions based on this address, rather than the address of the intermediate caching name server.

The option is transmitted as part of an OPTRecord in the additional section of a DNS message, as defined by RFC 6891 (EDNS0).

The wire format of the option contains a 2-byte length field (1 for IPv4, 2 for IPv6), a 1-byte source netmask, a 1-byte scope netmask, and an address truncated to the source netmask length (where the final octet is padded with bits set to 0)

Author:

Brian Wellington, Ming Zhou <mizhou@bnivideo.com>, Beaumaris Networks

See Also:

• OPTRecord
• RFC 7871

Nested Class Summary

Nested classes/interfaces inherited from class org.xbill.DNS.EDNSOption

EDNSOption.Code

Constructor Summary

Constructors

Constructor	Description
ClientSubnetOption(int sourcePrefixLength, int scopePrefixLength, InetAddress address)	Construct a Client Subnet option.
ClientSubnetOption(int sourcePrefixLength, InetAddress address)	Construct a Client Subnet option with scope netmask set to 0.

Method Summary

Modifier and Type	Method	Description
InetAddress	getAddress()	Returns the IP address of the client.
int	getFamily()	Returns the family of the network address.
int	getScopePrefixLength()	Returns the scope netmask.
int	getSourcePrefixLength()	Returns the source netmask.

Methods inherited from class org.xbill.DNS.EDNSOption

equals, fromWire, getCode, hashCode, toString, toWire

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

ClientSubnetOption

public ClientSubnetOption(int sourcePrefixLength,
 int scopePrefixLength,
 InetAddress address)

Construct a Client Subnet option. Note that the number of significant bits in the address must not be greater than the supplied source netmask. There may also be issues related to Java's handling of mapped addresses

Parameters:

sourcePrefixLength - The length of the netmask pertaining to the query. In replies, it mirrors the same value as in the requests.

scopePrefixLength - The length of the netmask pertaining to the reply. In requests, it MUST be set to 0. In responses, this may or may not match the source netmask.

address - The address of the client.

ClientSubnetOption

public ClientSubnetOption(int sourcePrefixLength,
 InetAddress address)

Construct a Client Subnet option with scope netmask set to 0.

Parameters:

sourcePrefixLength - The length of the netmask pertaining to the query. In replies, it mirrors the same value as in the requests.

address - The address of the client.

See Also:

• ClientSubnetOption

Method Details

getFamily

public int getFamily()

Returns the family of the network address. This will be either IPv4 (1) or IPv6 (2).

getSourcePrefixLength

public int getSourcePrefixLength()

Returns the source netmask.

getScopePrefixLength

public int getScopePrefixLength()

Returns the scope netmask.

getAddress

public InetAddress getAddress()

Returns the IP address of the client.