org.apache.hadoop.net
Class DNS

java.lang.Object
  org.apache.hadoop.net.DNS

public class DNS
extends Object

A class that provides direct and reverse lookup functionalities, allowing the querying of specific network interfaces or nameservers.

Field Summary

static org.apache.commons.logging.Log

LOG

Constructor Summary

DNS()

Method Summary

static String	getDefaultHost(String strInterface) Returns the default (first) host name associated by the default nameserver with the address bound to the specified network interface
static String	getDefaultHost(String strInterface, String nameserver) Returns the default (first) host name associated by the provided nameserver with the address bound to the specified network interface
static String	getDefaultIP(String strInterface) Returns the first available IP address associated with the provided network interface
static String[]	getHosts(String strInterface) Returns all the host names associated by the default nameserver with the address bound to the specified network interface
static String[]	getHosts(String strInterface, String nameserver) Returns all the host names associated by the provided nameserver with the address bound to the specified network interface
static String[]	getIPs(String strInterface) Like getIPs(String, boolean), but returns all IPs associated with the given interface and its subinterfaces.
static String[]	getIPs(String strInterface, boolean returnSubinterfaces) Returns all the IPs associated with the provided interface, if any, in textual form.
static String	reverseDns(InetAddress hostIp, String ns) Returns the hostname associated with the specified IP address by the provided nameserver.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

public static final org.apache.commons.logging.Log LOG

Constructor Detail

DNS

public DNS()

Method Detail

reverseDns

public static String reverseDns(InetAddress hostIp,
                                String ns)
                         throws NamingException

Returns the hostname associated with the specified IP address by the provided nameserver.

Parameters:

hostIp - The address to reverse lookup

ns - The host name of a reachable DNS server

Returns:

The host name associated with the provided IP

Throws:

NamingException - If a NamingException is encountered

getIPs

public static String[] getIPs(String strInterface)
                       throws UnknownHostException

Like getIPs(String, boolean), but returns all IPs associated with the given interface and its subinterfaces.

Throws:

UnknownHostException

getIPs

public static String[] getIPs(String strInterface,
                              boolean returnSubinterfaces)
                       throws UnknownHostException

Returns all the IPs associated with the provided interface, if any, in textual form.

Parameters:

strInterface - The name of the network interface or subinterface to query (eg eth0 or eth0:0) or the string "default"

returnSubinterfaces - Whether to return IPs associated with subinterfaces of the given interface

Returns:

A string vector of all the IPs associated with the provided interface

Throws:

UnknownHostException - If an UnknownHostException is encountered in querying the default interface or the given interface can not be found

getDefaultIP

public static String getDefaultIP(String strInterface)
                           throws UnknownHostException

Returns the first available IP address associated with the provided network interface

Parameters:

strInterface - The name of the network interface or subinterface to query (e.g. eth0 or eth0:0) or the string "default"

Returns:

The IP address in text form

Throws:

UnknownHostException - If one is encountered in querying the default interface

getHosts

public static String[] getHosts(String strInterface,
                                String nameserver)
                         throws UnknownHostException

Returns all the host names associated by the provided nameserver with the address bound to the specified network interface

Parameters:

strInterface - The name of the network interface or subinterface to query (e.g. eth0 or eth0:0) or the string "default"

nameserver - The DNS host name

Returns:

A string vector of all host names associated with the IPs tied to the specified interface

Throws:

UnknownHostException

getHosts

public static String[] getHosts(String strInterface)
                         throws UnknownHostException

Returns all the host names associated by the default nameserver with the address bound to the specified network interface

Parameters:

strInterface - The name of the network interface to query (e.g. eth0)

Returns:

The list of host names associated with IPs bound to the network interface

Throws:

UnknownHostException - If one is encountered while querying the deault interface

getDefaultHost

public static String getDefaultHost(String strInterface,
                                    String nameserver)
                             throws UnknownHostException

Returns the default (first) host name associated by the provided nameserver with the address bound to the specified network interface

Parameters:

strInterface - The name of the network interface to query (e.g. eth0)

nameserver - The DNS host name

Returns:

The default host names associated with IPs bound to the network interface

Throws:

UnknownHostException - If one is encountered while querying the deault interface

getDefaultHost

public static String getDefaultHost(String strInterface)
                             throws UnknownHostException

Returns the default (first) host name associated by the default nameserver with the address bound to the specified network interface

Parameters:

strInterface - The name of the network interface to query (e.g. eth0)

Returns:

The default host name associated with IPs bound to the network interface

Throws:

UnknownHostException - If one is encountered while querying the deault interface