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;
024
025import javax.crypto.Mac;
026import javax.crypto.spec.SecretKeySpec;
027
028import org.apache.commons.net.util.Base64;
029
030
031/**
032 * A POP3 Cilent class with protocol and authentication extensions support
033 * (RFC2449 and RFC2195).
034 * @see POP3Client
035 * @since 3.0
036 */
037public class ExtendedPOP3Client extends POP3SClient
038{
039    /**
040     * The default ExtendedPOP3Client constructor.
041     * Creates a new Extended POP3 Client.
042     * @throws NoSuchAlgorithmException on error
043     */
044    public ExtendedPOP3Client() throws NoSuchAlgorithmException
045    {
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}