org.apache.hadoop.security.Credentials.java Source code

Java tutorial

Introduction

Here is the source code for org.apache.hadoop.security.Credentials.java

Source

/**
 * 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.security;

import java.io.DataInput;
import java.io.DataInputStream;
import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.security.token.TokenIdentifier;

/**
 * A class that provides the facilities of reading and writing 
 * secret keys and Tokens.
 */
public class Credentials implements Writable {
    private static final Log LOG = LogFactory.getLog(Credentials.class);

    private Map<Text, byte[]> secretKeysMap = new HashMap<Text, byte[]>();
    private Map<Text, Token<? extends TokenIdentifier>> tokenMap = new HashMap<Text, Token<? extends TokenIdentifier>>();

    /**
     * Returns the key bytes for the alias
     * @param alias the alias for the key
     * @return key for this alias
     */
    public byte[] getSecretKey(Text alias) {
        return secretKeysMap.get(alias);
    }

    /**
     * Returns the Token object for the alias
     * @param alias the alias for the Token
     * @return token for this alias
     */
    public Token<? extends TokenIdentifier> getToken(Text alias) {
        return tokenMap.get(alias);
    }

    /**
     * Add a token in the storage (in memory)
     * @param alias the alias for the key
     * @param t the token object
     */
    public void addToken(Text alias, Token<? extends TokenIdentifier> t) {
        if (t != null) {
            tokenMap.put(alias, t);
        } else {
            LOG.warn("Null token ignored for " + alias);
        }
    }

    /**
     * Return all the tokens in the in-memory map
     */
    public Collection<Token<? extends TokenIdentifier>> getAllTokens() {
        return tokenMap.values();
    }

    /**
     * @return number of Tokens in the in-memory map
     */
    public int numberOfTokens() {
        return tokenMap.size();
    }

    /**
     * @return number of keys in the in-memory map
     */
    public int numberOfSecretKeys() {
        return secretKeysMap.size();
    }

    /**
     * Set the key for an alias
     * @param alias the alias for the key
     * @param key the key bytes
     */
    public void addSecretKey(Text alias, byte[] key) {
        secretKeysMap.put(alias, key);
    }

    /**
     * Convenience method for reading a token storage file, and loading the Tokens
     * therein in the passed UGI
     * @param filename
     * @param conf
     * @throws IOException
     */
    public static Credentials readTokenStorageFile(Path filename, Configuration conf) throws IOException {
        FSDataInputStream in = null;
        Credentials credentials = new Credentials();
        try {
            in = filename.getFileSystem(conf).open(filename);
            credentials.readTokenStorageStream(in);
            in.close();
            return credentials;
        } catch (IOException ioe) {
            IOUtils.cleanup(LOG, in);
            throw new IOException("Exception reading " + filename, ioe);
        }
    }

    /**
     * Convenience method for reading a token storage file directly from a 
     * datainputstream
     */
    public void readTokenStorageStream(DataInputStream in) throws IOException {
        byte[] magic = new byte[TOKEN_STORAGE_MAGIC.length];
        in.readFully(magic);
        if (!Arrays.equals(magic, TOKEN_STORAGE_MAGIC)) {
            throw new IOException("Bad header found in token storage.");
        }
        byte version = in.readByte();
        if (version != TOKEN_STORAGE_VERSION) {
            throw new IOException("Unknown version " + version + " in token storage.");
        }
        readFields(in);
    }

    private static final byte[] TOKEN_STORAGE_MAGIC = "HDTS".getBytes();
    private static final byte TOKEN_STORAGE_VERSION = 0;

    public void writeTokenStorageToStream(DataOutputStream os) throws IOException {
        os.write(TOKEN_STORAGE_MAGIC);
        os.write(TOKEN_STORAGE_VERSION);
        write(os);
    }

    public void writeTokenStorageFile(Path filename, Configuration conf) throws IOException {
        FSDataOutputStream os = filename.getFileSystem(conf).create(filename);
        writeTokenStorageToStream(os);
        os.close();
    }

    /**
     * Stores all the keys to DataOutput
     * @param out
     * @throws IOException
     */
    @Override
    public void write(DataOutput out) throws IOException {
        // write out tokens first
        WritableUtils.writeVInt(out, tokenMap.size());
        for (Map.Entry<Text, Token<? extends TokenIdentifier>> e : tokenMap.entrySet()) {
            e.getKey().write(out);
            e.getValue().write(out);
        }

        // now write out secret keys
        WritableUtils.writeVInt(out, secretKeysMap.size());
        for (Map.Entry<Text, byte[]> e : secretKeysMap.entrySet()) {
            e.getKey().write(out);
            WritableUtils.writeVInt(out, e.getValue().length);
            out.write(e.getValue());
        }
    }

    /**
     * Loads all the keys
     * @param in
     * @throws IOException
     */
    @Override
    public void readFields(DataInput in) throws IOException {
        secretKeysMap.clear();
        tokenMap.clear();

        int size = WritableUtils.readVInt(in);
        for (int i = 0; i < size; i++) {
            Text alias = new Text();
            alias.readFields(in);
            Token<? extends TokenIdentifier> t = new Token<TokenIdentifier>();
            t.readFields(in);
            tokenMap.put(alias, t);
        }

        size = WritableUtils.readVInt(in);
        for (int i = 0; i < size; i++) {
            Text alias = new Text();
            alias.readFields(in);
            int len = WritableUtils.readVInt(in);
            byte[] value = new byte[len];
            in.readFully(value);
            secretKeysMap.put(alias, value);
        }
    }

    /**
     * Copy all of the credentials from one credential object into another.
     * @param other the credentials to copy
     */
    public void addAll(Credentials other) {
        for (Map.Entry<Text, byte[]> secret : other.secretKeysMap.entrySet()) {
            secretKeysMap.put(secret.getKey(), secret.getValue());
        }
        for (Map.Entry<Text, Token<?>> token : other.tokenMap.entrySet()) {
            tokenMap.put(token.getKey(), token.getValue());
        }
    }
}