/*
* Copyright (C) 2010 Wayne Meissner
*
* This file is part of jnr.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jnr.netdb;
import java.util.
Collection;
/**
* An entry in the system protocol database
*/
public final class
Protocol {
/** Official protocol name */
private final
String protocolName;
private final int
proto;
/** All the aliases for this protocol */
private final
Collection<
String>
aliases;
Protocol(
String name, int
proto,
Collection<
String>
aliases) {
this.
protocolName =
name;
this.
proto =
proto;
this.
aliases =
aliases;
}
/**
* Locates a protocol by name.
*
* @param name the official IANA name for the protocol, or an alias.
* @return a {@code Protocol} instance, or {@code null} if the protocol could not be found.
*/
public static final
Protocol getProtocolByName(
String name) {
return
getProtocolDB().
getProtocolByName(
name);
}
/**
* Locates a protocol by number.
*
* @param proto the internet protocol number of the protocol.
* @return a {@code Protocol} instance, or {@code null} if the protocol could not be found.
*/
public static final
Protocol getProtocolByNumber(int
proto) {
return
getProtocolDB().
getProtocolByNumber(
proto);
}
/**
* Returns the official IANA name of this {@code Protocol}
*
* @return The name of this {@code Protocol} as a {@code String}
*/
public final
String getName() {
return
protocolName;
}
/**
* Returns the official IANA protocol number for this {@code Protocol}
*
* @return The protocol number for this {@code Protocol} as an {@code int}
*/
public final int
getProto() {
return
proto;
}
/**
* Returns a list of aliases this {@code Protocol} is also known by.
*
* @return A {@code Collection} of Strings for aliases this {@code Protocol}
*/
public final
Collection<
String>
getAliases() {
return
aliases;
}
/**
* Returns the currently loaded ProtocolDB
*
* @return an instance of {@code ProtocolDB}
*/
private static final
ProtocolsDB getProtocolDB() {
return
ProtocolDBSingletonHolder.
INSTANCE;
}
/**
* Holds the global lazily-loaded instance of the ProtocolDB
*/
private static final class
ProtocolDBSingletonHolder {
static final
ProtocolsDB INSTANCE =
load();
private static final
ProtocolsDB load() {
// Try to use the native functions if possible
ProtocolsDB db =
NativeProtocolsDB.
getInstance();
// Fall back to parsing /etc/protocols directly.
if (
db == null) {
db =
FileProtocolsDB.
getInstance();
}
// As a last resort, fall back to the hard coded table
return
db != null ?
db :
IANAProtocolsDB.
getInstance();
}
}
@
Override
public
String toString() {
return
String.
format("<Protocol: Name: %s, Proto: %d, Aliases: %s>",
protocolName,
proto,
aliases);
};
}