    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.net.pop3;
    019
    020import java.io.IOException;
    021import java.security.InvalidKeyException;
    022import java.security.NoSuchAlgorithmException;
    023import java.security.spec.InvalidKeySpecException;
    024import javax.crypto.Mac;
    025import javax.crypto.spec.SecretKeySpec;
    026
    027import org.apache.commons.net.util.Base64;
    028
    029
    030/**
    031 * A POP3 Cilent class with protocol and authentication extensions support
    032 * (RFC2449 and RFC2195).
    033 * @see POP3Client
    034 * @since 3.0
    035 */
    036public class ExtendedPOP3Client extends POP3SClient
    037{
    038    /**
    039     * The default ExtendedPOP3Client constructor.
    040     * Creates a new Extended POP3 Client.
    041     * @throws NoSuchAlgorithmException on error
    042     */
    043    public ExtendedPOP3Client() throws NoSuchAlgorithmException
    044    {
    045        super();
    046    }
    047
    048    /***
    049     * Authenticate to the POP3 server by sending the AUTH command with the
    050     * selected mechanism, using the given username and the given password.
    051     * <p>
    052     * @param method the {@link AUTH_METHOD} to use
    053     * @param username the user name
    054     * @param password the password
    055     * @return True if successfully completed, false if not.
    056     * @throws IOException  If an I/O error occurs while either sending a
    057     *      command to the server or receiving a reply from the server.
    058     * @throws NoSuchAlgorithmException If the CRAM hash algorithm
    059     *      cannot be instantiated by the Java runtime system.
    060     * @throws InvalidKeyException If the CRAM hash algorithm
    061     *      failed to use the given password.
    062     * @throws InvalidKeySpecException If the CRAM hash algorithm
    063     *      failed to use the given password.
    064     ***/
    065    public boolean auth(final AUTH_METHOD method,
    066                        final String username, final String password)
    067                        throws IOException, NoSuchAlgorithmException,
    068                        InvalidKeyException, InvalidKeySpecException
    069    {
    070        if (sendCommand(POP3Command.AUTH, method.getAuthName())
    071        != POP3Reply.OK_INT) {
    072            return false;
    073        }
    074
    075        switch(method) {
    076            case PLAIN:
    077                // the server sends an empty response ("+ "), so we don't have to read it.
    078                return sendCommand(
    079                    new String(
    080                        Base64.encodeBase64(("\000" + username + "\000" + password).getBytes(getCharset())),
    081                        getCharset())
    082                    ) == POP3Reply.OK;
    083            case CRAM_MD5:
    084                // get the CRAM challenge
    085                final byte[] serverChallenge = Base64.decodeBase64(getReplyString().substring(2).trim());
    086                // get the Mac instance
    087                final Mac hmac_md5 = Mac.getInstance("HmacMD5");
    088                hmac_md5.init(new SecretKeySpec(password.getBytes(getCharset()), "HmacMD5"));
    089                // compute the result:
    090                final byte[] hmacResult = convertToHexString(hmac_md5.doFinal(serverChallenge)).getBytes(getCharset());
    091                // join the byte arrays to form the reply
    092                final byte[] usernameBytes = username.getBytes(getCharset());
    093                final byte[] toEncode = new byte[usernameBytes.length + 1 /* the space */ + hmacResult.length];
    094                System.arraycopy(usernameBytes, 0, toEncode, 0, usernameBytes.length);
    095                toEncode[usernameBytes.length] = ' ';
    096                System.arraycopy(hmacResult, 0, toEncode, usernameBytes.length + 1, hmacResult.length);
    097                // send the reply and read the server code:
    098                return sendCommand(Base64.encodeBase64StringUnChunked(toEncode)) == POP3Reply.OK;
    099            default:
    100                return false;
    101        }
    102    }
    103
    104    /**
    105     * Converts the given byte array to a String containing the hex values of the bytes.
    106     * For example, the byte 'A' will be converted to '41', because this is the ASCII code
    107     * (and the byte value) of the capital letter 'A'.
    108     * @param a The byte array to convert.
    109     * @return The resulting String of hex codes.
    110     */
    111    private String convertToHexString(final byte[] a)
    112    {
    113        final StringBuilder result = new StringBuilder(a.length*2);
    114        for (final byte element : a)
    115        {
    116            if ( (element & 0x0FF) <= 15 ) {
    117                result.append("0");
    118            }
    119            result.append(Integer.toHexString(element & 0x0FF));
    120        }
    121        return result.toString();
    122    }
    123
    124    /**
    125     * The enumeration of currently-supported authentication methods.
    126     */
    127    public enum AUTH_METHOD
    128    {
    129        /** The standarised (RFC4616) PLAIN method, which sends the password unencrypted (insecure). */
    130        PLAIN("PLAIN"),
    131
    132        /** The standarised (RFC2195) CRAM-MD5 method, which doesn't send the password (secure). */
    133        CRAM_MD5("CRAM-MD5");
    134
    135        private final String methodName;
    136
    137        AUTH_METHOD(final String methodName){
    138            this.methodName = methodName;
    139        }
    140        /**
    141         * Gets the name of the given authentication method suitable for the server.
    142         * @return The name of the given authentication method suitable for the server.
    143         */
    144        public final String getAuthName()
    145        {
    146            return this.methodName;
    147        }
    148    }
    149}