/*
* Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package sun.net.dns;
import java.util.List;
import java.io.IOException;
/**
* The configuration of the client resolver.
*
* <p>A ResolverConfiguration is a singleton that represents the
* configuration of the client resolver. The ResolverConfiguration
* is opened by invoking the {@link #open() open} method.
*
* @since 1.4
*/
public abstract class ResolverConfiguration {
private static final Object lock = new Object();
private static ResolverConfiguration provider;
protected ResolverConfiguration() { }
/**
* Opens the resolver configuration.
*
* @return the resolver configuration
*/
public static ResolverConfiguration open() {
synchronized (lock) {
if (provider == null) {
provider = new sun.net.dns.ResolverConfigurationImpl();
}
return provider;
}
}
/**
* Returns a list corresponding to the domain search path. The
* list is ordered by the search order used for host name lookup.
* Each element in the list returns a {@link java.lang.String}
* containing a domain name or suffix.
*
* @return list of domain names
*/
public abstract List searchlist();
/**
* Returns a list of name servers used for host name lookup.
* Each element in the list returns a {@link java.lang.String}
* containing the textual representation of the IP address of
* the name server.
*
* @return list of the name servers
*/
public abstract List nameservers();
/**
* Options representing certain resolver variables of
* a {@link ResolverConfiguration}.
*/
public static abstract class Options {
/**
* Returns the maximum number of attempts the resolver
* will connect to each name server before giving up
* and returning an error.
*
* @return the resolver attempts value or -1 is unknown
*/
public int attempts() {
return -1;
}
/**
* Returns the basic retransmit timeout, in milliseconds,
* used by the resolver. The resolver will typically use
* an exponential backoff algorithm where the timeout is
* doubled for every retransmit attempt. The basic
* retransmit timeout, returned here, is the initial
* timeout for the exponential backoff algorithm.
*
* @return the basic retransmit timeout value or -1
* if unknown
*/
public int retrans() {
return -1;
}
}
/**
* Returns the {@link #Options} for the resolver.
*
* @return options for the resolver
*/
public abstract Options options();
}