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 *      https://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.util.Base64;
024
025import javax.crypto.Mac;
026import javax.crypto.spec.SecretKeySpec;
027import javax.net.ssl.SSLContext;
028
029/**
030 * An IMAP Client class with authentication support.
031 *
032 * @see IMAPSClient
033 */
034public class AuthenticatingIMAPClient extends IMAPSClient {
035
036    /**
037     * The enumeration of currently-supported authentication methods.
038     */
039    public enum AUTH_METHOD {
040
041        /** The standardized (RFC4616) PLAIN method, which sends the password unencrypted (insecure). */
042
043        PLAIN("PLAIN"),
044
045        /** The standardized (RFC2195) CRAM-MD5 method, which doesn't send the password (secure). */
046
047        CRAM_MD5("CRAM-MD5"),
048
049        /** The standardized Microsoft LOGIN method, which sends the password unencrypted (insecure). */
050        LOGIN("LOGIN"),
051
052        /** XOAUTH */
053        XOAUTH("XOAUTH"),
054
055        /** XOAUTH 2 */
056        XOAUTH2("XOAUTH2");
057
058        private final String authName;
059
060        AUTH_METHOD(final String name) {
061            this.authName = name;
062        }
063
064        /**
065         * Gets the name of the given authentication method suitable for the server.
066         *
067         * @return The name of the given authentication method suitable for the server.
068         */
069        public String getAuthName() {
070            return authName;
071        }
072    }
073
074    /** {@link Mac} algorithm. */
075    private static final String MAC_ALGORITHM = "HmacMD5";
076
077    /**
078     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient. Sets security mode to explicit (isImplicit = false).
079     */
080    public AuthenticatingIMAPClient() {
081        this(DEFAULT_PROTOCOL, false);
082    }
083
084    /**
085     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
086     *
087     * @param implicit The security mode (Implicit/Explicit).
088     */
089    public AuthenticatingIMAPClient(final boolean implicit) {
090        this(DEFAULT_PROTOCOL, implicit);
091    }
092
093    /**
094     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
095     *
096     * @param implicit The security mode(Implicit/Explicit).
097     * @param ctx      A pre-configured SSL Context.
098     */
099    public AuthenticatingIMAPClient(final boolean implicit, final SSLContext ctx) {
100        this(DEFAULT_PROTOCOL, implicit, ctx);
101    }
102
103    /**
104     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
105     *
106     * @param context A pre-configured SSL Context.
107     */
108    public AuthenticatingIMAPClient(final SSLContext context) {
109        this(false, context);
110    }
111
112    /**
113     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
114     *
115     * @param proto the protocol.
116     */
117    public AuthenticatingIMAPClient(final String proto) {
118        this(proto, false);
119    }
120
121    /**
122     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
123     *
124     * @param proto    the protocol.
125     * @param implicit The security mode(Implicit/Explicit).
126     */
127    public AuthenticatingIMAPClient(final String proto, final boolean implicit) {
128        this(proto, implicit, null);
129    }
130
131    /**
132     * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
133     *
134     * @param proto    the protocol.
135     * @param implicit The security mode(Implicit/Explicit).
136     * @param ctx      the context
137     */
138    public AuthenticatingIMAPClient(final String proto, final boolean implicit, final SSLContext ctx) {
139        super(proto, implicit, ctx);
140    }
141
142    /**
143     * Authenticate to the IMAP server by sending the AUTHENTICATE command with the selected mechanism, using the given user and the given password.
144     *
145     * @param method   the method name
146     * @param user user
147     * @param password password
148     * @return True if successfully completed, false if not.
149     * @throws IOException              If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
150     * @throws NoSuchAlgorithmException If the CRAM hash algorithm cannot be instantiated by the Java runtime system.
151     * @throws InvalidKeyException      If the CRAM hash algorithm failed to use the given password.
152     */
153    public boolean auth(final AuthenticatingIMAPClient.AUTH_METHOD method, final String user, final String password)
154            throws IOException, NoSuchAlgorithmException, InvalidKeyException {
155        if (!IMAPReply.isContinuation(sendCommand(IMAPCommand.AUTHENTICATE, method.getAuthName()))) {
156            return false;
157        }
158
159        switch (method) {
160        case PLAIN: {
161            // the server sends an empty response ("+ "), so we don't have to read it.
162            final int result = sendData(Base64.getEncoder().encodeToString(("\000" + user + "\000" + password).getBytes(getCharset())));
163            if (result == IMAPReply.OK) {
164                setState(IMAP.IMAPState.AUTH_STATE);
165            }
166            return result == IMAPReply.OK;
167        }
168        case CRAM_MD5: {
169            // get the CRAM challenge (after "+ ")
170            final byte[] serverChallenge = Base64.getDecoder().decode(getReplyString().substring(2).trim());
171            // get the Mac instance
172            final Mac hmacMd5 = Mac.getInstance(MAC_ALGORITHM);
173            hmacMd5.init(new SecretKeySpec(password.getBytes(getCharset()), MAC_ALGORITHM));
174            // compute the result:
175            final byte[] hmacResult = convertToHexString(hmacMd5.doFinal(serverChallenge)).getBytes(getCharset());
176            // join the byte arrays to form the reply
177            final byte[] usernameBytes = user.getBytes(getCharset());
178            final byte[] toEncode = new byte[usernameBytes.length + 1 /* the space */ + hmacResult.length];
179            System.arraycopy(usernameBytes, 0, toEncode, 0, usernameBytes.length);
180            toEncode[usernameBytes.length] = ' ';
181            System.arraycopy(hmacResult, 0, toEncode, usernameBytes.length + 1, hmacResult.length);
182            // send the reply and read the server code:
183            final int result = sendData(Base64.getEncoder().encodeToString(toEncode));
184            if (result == IMAPReply.OK) {
185                setState(IMAP.IMAPState.AUTH_STATE);
186            }
187            return result == IMAPReply.OK;
188        }
189        case LOGIN: {
190            // the server sends fixed responses (base64("UserName") and
191            // base64("Password")), so we don't have to read them.
192            if (sendData(Base64.getEncoder().encodeToString(user.getBytes(getCharset()))) != IMAPReply.CONT) {
193                return false;
194            }
195            final int result = sendData(Base64.getEncoder().encodeToString(password.getBytes(getCharset())));
196            if (result == IMAPReply.OK) {
197                setState(IMAP.IMAPState.AUTH_STATE);
198            }
199            return result == IMAPReply.OK;
200        }
201        case XOAUTH:
202        case XOAUTH2: {
203            final int result = sendData(user);
204            if (result == IMAPReply.OK) {
205                setState(IMAP.IMAPState.AUTH_STATE);
206            }
207            return result == IMAPReply.OK;
208        }
209        }
210        return false; // safety check
211    }
212
213    /**
214     * Authenticate to the IMAP server by sending the AUTHENTICATE command with the selected mechanism, using the given user and the given password.
215     *
216     * @param method   the method name
217     * @param user user
218     * @param password password
219     * @return True if successfully completed, false if not.
220     * @throws IOException              If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
221     * @throws NoSuchAlgorithmException If the CRAM hash algorithm cannot be instantiated by the Java runtime system.
222     * @throws InvalidKeyException      If the CRAM hash algorithm failed to use the given password.
223     */
224    public boolean authenticate(final AuthenticatingIMAPClient.AUTH_METHOD method, final String user, final String password)
225            throws IOException, NoSuchAlgorithmException, InvalidKeyException {
226        return auth(method, user, password);
227    }
228
229    /**
230     * Converts the given byte array to a String containing the hexadecimal values of the bytes. For example, the byte 'A' will be converted to '41', because
231     * this is the ASCII code (and the byte value) of the capital letter 'A'.
232     *
233     * @param a The byte array to convert.
234     * @return The resulting String of hexadecimal codes.
235     */
236    private String convertToHexString(final byte[] a) {
237        final StringBuilder result = new StringBuilder(a.length * 2);
238        for (final byte element : a) {
239            if ((element & 0x0FF) <= 15) {
240                result.append("0");
241            }
242            result.append(Integer.toHexString(element & 0x0FF));
243        }
244        return result.toString();
245    }
246}
247