org.apache.hadoop.crypto.key.KeyProviderDelegationTokenExtension.java Source code

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Here is the source code for org.apache.hadoop.crypto.key.KeyProviderDelegationTokenExtension.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.hadoop.crypto.key;

import com.google.common.annotations.VisibleForTesting;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.security.Credentials;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.security.token.DelegationTokenIssuer;

import java.io.IOException;

/**
 * A KeyProvider extension with the ability to add a renewer's Delegation 
 * Tokens to the provided Credentials.
 */
public class KeyProviderDelegationTokenExtension
        extends KeyProviderExtension<KeyProviderDelegationTokenExtension.DelegationTokenExtension>
        implements DelegationTokenIssuer {

    private static DelegationTokenExtension DEFAULT_EXTENSION = new DefaultDelegationTokenExtension();

    /**
     * DelegationTokenExtension is a type of Extension that exposes methods
     * needed to work with Delegation Tokens.
     */
    public interface DelegationTokenExtension extends KeyProviderExtension.Extension, DelegationTokenIssuer {
        /**
         * Renews the given token.
         * @param token The token to be renewed.
         * @return The token's lifetime after renewal, or 0 if it can't be renewed.
         * @throws IOException
         */
        long renewDelegationToken(final Token<?> token) throws IOException;

        /**
         * Cancels the given token.
         * @param token The token to be cancelled.
         * @throws IOException
         */
        Void cancelDelegationToken(final Token<?> token) throws IOException;

        // Do NOT call this. Only intended for internal use.
        @VisibleForTesting
        @InterfaceAudience.Private
        @InterfaceStability.Unstable
        Token<?> selectDelegationToken(Credentials creds);
    }

    /**
     * Default implementation of {@link DelegationTokenExtension} that
     * implements the method as a no-op.
     */
    private static class DefaultDelegationTokenExtension implements DelegationTokenExtension {

        @Override
        public Token<?>[] addDelegationTokens(String renewer, Credentials credentials) {
            return null;
        }

        @Override
        public String getCanonicalServiceName() {
            return null;
        }

        @Override
        public Token<?> getDelegationToken(String renewer) {
            return null;
        }

        @Override
        public long renewDelegationToken(final Token<?> token) throws IOException {
            return 0;
        }

        @Override
        public Void cancelDelegationToken(final Token<?> token) throws IOException {
            return null;
        }

        @Override
        public Token<?> selectDelegationToken(Credentials creds) {
            return null;
        }

    }

    private KeyProviderDelegationTokenExtension(KeyProvider keyProvider, DelegationTokenExtension extensions) {
        super(keyProvider, extensions);
    }

    @Override
    public String getCanonicalServiceName() {
        return getExtension().getCanonicalServiceName();
    }

    @Override
    public Token<?> getDelegationToken(final String renewer) throws IOException {
        return getExtension().getDelegationToken(renewer);
    }

    /**
     * Creates a <code>KeyProviderDelegationTokenExtension</code> using a given 
     * {@link KeyProvider}.
     * <p/>
     * If the given <code>KeyProvider</code> implements the 
     * {@link DelegationTokenExtension} interface the <code>KeyProvider</code> 
     * itself will provide the extension functionality, otherwise a default 
     * extension implementation will be used.
     * 
     * @param keyProvider <code>KeyProvider</code> to use to create the 
     * <code>KeyProviderDelegationTokenExtension</code> extension.
     * @return a <code>KeyProviderDelegationTokenExtension</code> instance 
     * using the given <code>KeyProvider</code>.
     */
    public static KeyProviderDelegationTokenExtension createKeyProviderDelegationTokenExtension(
            KeyProvider keyProvider) {

        DelegationTokenExtension delTokExtension = (keyProvider instanceof DelegationTokenExtension)
                ? (DelegationTokenExtension) keyProvider
                : DEFAULT_EXTENSION;
        return new KeyProviderDelegationTokenExtension(keyProvider, delTokExtension);

    }

}