    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.imap;
    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;
    027import javax.net.ssl.SSLContext;
    028
    029import org.apache.commons.net.util.Base64;
    030
    031/**
    032 * An IMAP Client class with authentication support.
    033 *
    034 * @see IMAPSClient
    035 */
    036public class AuthenticatingIMAPClient extends IMAPSClient {
    037    /**
    038     * The enumeration of currently-supported authentication methods.
    039     */
    040    public enum AUTH_METHOD {
    041        /** The standarised (RFC4616) PLAIN method, which sends the password unencrypted (insecure). */
    042        PLAIN("PLAIN"),
    043        /** The standarised (RFC2195) CRAM-MD5 method, which doesn't send the password (secure). */
    044        CRAM_MD5("CRAM-MD5"),
    045        /** The unstandarised Microsoft LOGIN method, which sends the password unencrypted (insecure). */
    046        LOGIN("LOGIN"),
    047        /** XOAUTH */
    048        XOAUTH("XOAUTH"),
    049        /** XOAUTH 2 */
    050        XOAUTH2("XOAUTH2");
    051
    052        private final String authName;
    053
    054        AUTH_METHOD(final String name) {
    055            this.authName = name;
    056        }
    057
    058        /**
    059         * Gets the name of the given authentication method suitable for the server.
    060         *
    061         * @return The name of the given authentication method suitable for the server.
    062         */
    063        public final String getAuthName() {
    064            return authName;
    065        }
    066    }
    067
    068    /**
    069     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient. Sets security mode to explicit (isImplicit = false).
    070     */
    071    public AuthenticatingIMAPClient() {
    072        this(DEFAULT_PROTOCOL, false);
    073    }
    074
    075    /**
    076     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
    077     *
    078     * @param implicit The security mode (Implicit/Explicit).
    079     */
    080    public AuthenticatingIMAPClient(final boolean implicit) {
    081        this(DEFAULT_PROTOCOL, implicit);
    082    }
    083
    084    /**
    085     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
    086     *
    087     * @param implicit The security mode(Implicit/Explicit).
    088     * @param ctx      A pre-configured SSL Context.
    089     */
    090    public AuthenticatingIMAPClient(final boolean implicit, final SSLContext ctx) {
    091        this(DEFAULT_PROTOCOL, implicit, ctx);
    092    }
    093
    094    /**
    095     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
    096     *
    097     * @param context A pre-configured SSL Context.
    098     */
    099    public AuthenticatingIMAPClient(final SSLContext context) {
    100        this(false, context);
    101    }
    102
    103    /**
    104     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
    105     *
    106     * @param proto the protocol.
    107     */
    108    public AuthenticatingIMAPClient(final String proto) {
    109        this(proto, false);
    110    }
    111
    112    /**
    113     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
    114     *
    115     * @param proto    the protocol.
    116     * @param implicit The security mode(Implicit/Explicit).
    117     */
    118    public AuthenticatingIMAPClient(final String proto, final boolean implicit) {
    119        this(proto, implicit, null);
    120    }
    121
    122    /**
    123     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
    124     *
    125     * @param proto    the protocol.
    126     * @param implicit The security mode(Implicit/Explicit).
    127     * @param ctx      the context
    128     */
    129    public AuthenticatingIMAPClient(final String proto, final boolean implicit, final SSLContext ctx) {
    130        super(proto, implicit, ctx);
    131    }
    132
    133    /**
    134     * Authenticate to the IMAP server by sending the AUTHENTICATE command with the selected mechanism, using the given username and the given password.
    135     *
    136     * @param method   the method name
    137     * @param username user
    138     * @param password password
    139     * @return True if successfully completed, false if not.
    140     * @throws IOException              If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
    141     * @throws NoSuchAlgorithmException If the CRAM hash algorithm cannot be instantiated by the Java runtime system.
    142     * @throws InvalidKeyException      If the CRAM hash algorithm failed to use the given password.
    143     * @throws InvalidKeySpecException  If the CRAM hash algorithm failed to use the given password.
    144     */
    145    public boolean auth(final AuthenticatingIMAPClient.AUTH_METHOD method, final String username, final String password)
    146            throws IOException, NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
    147        if (!IMAPReply.isContinuation(sendCommand(IMAPCommand.AUTHENTICATE, method.getAuthName()))) {
    148            return false;
    149        }
    150
    151        switch (method) {
    152        case PLAIN: {
    153            // the server sends an empty response ("+ "), so we don't have to read it.
    154            final int result = sendData(Base64.encodeBase64StringUnChunked(("\000" + username + "\000" + password).getBytes(getCharset())));
    155            if (result == IMAPReply.OK) {
    156                setState(IMAP.IMAPState.AUTH_STATE);
    157            }
    158            return result == IMAPReply.OK;
    159        }
    160        case CRAM_MD5: {
    161            // get the CRAM challenge (after "+ ")
    162            final byte[] serverChallenge = Base64.decodeBase64(getReplyString().substring(2).trim());
    163            // get the Mac instance
    164            final Mac hmac_md5 = Mac.getInstance("HmacMD5");
    165            hmac_md5.init(new SecretKeySpec(password.getBytes(getCharset()), "HmacMD5"));
    166            // compute the result:
    167            final byte[] hmacResult = convertToHexString(hmac_md5.doFinal(serverChallenge)).getBytes(getCharset());
    168            // join the byte arrays to form the reply
    169            final byte[] usernameBytes = username.getBytes(getCharset());
    170            final byte[] toEncode = new byte[usernameBytes.length + 1 /* the space */ + hmacResult.length];
    171            System.arraycopy(usernameBytes, 0, toEncode, 0, usernameBytes.length);
    172            toEncode[usernameBytes.length] = ' ';
    173            System.arraycopy(hmacResult, 0, toEncode, usernameBytes.length + 1, hmacResult.length);
    174            // send the reply and read the server code:
    175            final int result = sendData(Base64.encodeBase64StringUnChunked(toEncode));
    176            if (result == IMAPReply.OK) {
    177                setState(IMAP.IMAPState.AUTH_STATE);
    178            }
    179            return result == IMAPReply.OK;
    180        }
    181        case LOGIN: {
    182            // the server sends fixed responses (base64("Username") and
    183            // base64("Password")), so we don't have to read them.
    184            if (sendData(Base64.encodeBase64StringUnChunked(username.getBytes(getCharset()))) != IMAPReply.CONT) {
    185                return false;
    186            }
    187            final int result = sendData(Base64.encodeBase64StringUnChunked(password.getBytes(getCharset())));
    188            if (result == IMAPReply.OK) {
    189                setState(IMAP.IMAPState.AUTH_STATE);
    190            }
    191            return result == IMAPReply.OK;
    192        }
    193        case XOAUTH:
    194        case XOAUTH2: {
    195            final int result = sendData(username);
    196            if (result == IMAPReply.OK) {
    197                setState(IMAP.IMAPState.AUTH_STATE);
    198            }
    199            return result == IMAPReply.OK;
    200        }
    201        }
    202        return false; // safety check
    203    }
    204
    205    /**
    206     * Authenticate to the IMAP server by sending the AUTHENTICATE command with the selected mechanism, using the given username and the given password.
    207     *
    208     * @param method   the method name
    209     * @param username user
    210     * @param password password
    211     * @return True if successfully completed, false if not.
    212     * @throws IOException              If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
    213     * @throws NoSuchAlgorithmException If the CRAM hash algorithm cannot be instantiated by the Java runtime system.
    214     * @throws InvalidKeyException      If the CRAM hash algorithm failed to use the given password.
    215     * @throws InvalidKeySpecException  If the CRAM hash algorithm failed to use the given password.
    216     */
    217    public boolean authenticate(final AuthenticatingIMAPClient.AUTH_METHOD method, final String username, final String password)
    218            throws IOException, NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
    219        return auth(method, username, password);
    220    }
    221
    222    /**
    223     * Converts the given byte array to a String containing the hex values of the bytes. For example, the byte 'A' will be converted to '41', because this is
    224     * the ASCII code (and the byte value) of the capital letter 'A'.
    225     *
    226     * @param a The byte array to convert.
    227     * @return The resulting String of hex codes.
    228     */
    229    private String convertToHexString(final byte[] a) {
    230        final StringBuilder result = new StringBuilder(a.length * 2);
    231        for (final byte element : a) {
    232            if ((element & 0x0FF) <= 15) {
    233                result.append("0");
    234            }
    235            result.append(Integer.toHexString(element & 0x0FF));
    236        }
    237        return result.toString();
    238    }
    239}
    240/* kate: indent-width 4; replace-tabs on; */