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;
024import java.util.Base64;
025
026import javax.crypto.Mac;
027import javax.crypto.spec.SecretKeySpec;
028import javax.net.ssl.SSLContext;
029
030/**
031 * An IMAP Client class with authentication support.
032 *
033 * @see IMAPSClient
034 */
035public class AuthenticatingIMAPClient extends IMAPSClient {
036
037    /**
038     * The enumeration of currently-supported authentication methods.
039     */
040    public enum AUTH_METHOD {
041
042        /** The standardized (RFC4616) PLAIN method, which sends the password unencrypted (insecure). */
043
044        PLAIN("PLAIN"),
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 final 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     * @throws InvalidKeySpecException  If the CRAM hash algorithm failed to use the given password.
153     */
154    public boolean auth(final AuthenticatingIMAPClient.AUTH_METHOD method, final String user, final String password)
155            throws IOException, NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
156        if (!IMAPReply.isContinuation(sendCommand(IMAPCommand.AUTHENTICATE, method.getAuthName()))) {
157            return false;
158        }
159
160        switch (method) {
161        case PLAIN: {
162            // the server sends an empty response ("+ "), so we don't have to read it.
163            final int result = sendData(Base64.getEncoder().encodeToString(("\000" + user + "\000" + password).getBytes(getCharset())));
164            if (result == IMAPReply.OK) {
165                setState(IMAP.IMAPState.AUTH_STATE);
166            }
167            return result == IMAPReply.OK;
168        }
169        case CRAM_MD5: {
170            // get the CRAM challenge (after "+ ")
171            final byte[] serverChallenge = Base64.getDecoder().decode(getReplyString().substring(2).trim());
172            // get the Mac instance
173            final Mac hmacMd5 = Mac.getInstance(MAC_ALGORITHM);
174            hmacMd5.init(new SecretKeySpec(password.getBytes(getCharset()), MAC_ALGORITHM));
175            // compute the result:
176            final byte[] hmacResult = convertToHexString(hmacMd5.doFinal(serverChallenge)).getBytes(getCharset());
177            // join the byte arrays to form the reply
178            final byte[] usernameBytes = user.getBytes(getCharset());
179            final byte[] toEncode = new byte[usernameBytes.length + 1 /* the space */ + hmacResult.length];
180            System.arraycopy(usernameBytes, 0, toEncode, 0, usernameBytes.length);
181            toEncode[usernameBytes.length] = ' ';
182            System.arraycopy(hmacResult, 0, toEncode, usernameBytes.length + 1, hmacResult.length);
183            // send the reply and read the server code:
184            final int result = sendData(Base64.getEncoder().encodeToString(toEncode));
185            if (result == IMAPReply.OK) {
186                setState(IMAP.IMAPState.AUTH_STATE);
187            }
188            return result == IMAPReply.OK;
189        }
190        case LOGIN: {
191            // the server sends fixed responses (base64("UserName") and
192            // base64("Password")), so we don't have to read them.
193            if (sendData(Base64.getEncoder().encodeToString(user.getBytes(getCharset()))) != IMAPReply.CONT) {
194                return false;
195            }
196            final int result = sendData(Base64.getEncoder().encodeToString(password.getBytes(getCharset())));
197            if (result == IMAPReply.OK) {
198                setState(IMAP.IMAPState.AUTH_STATE);
199            }
200            return result == IMAPReply.OK;
201        }
202        case XOAUTH:
203        case XOAUTH2: {
204            final int result = sendData(user);
205            if (result == IMAPReply.OK) {
206                setState(IMAP.IMAPState.AUTH_STATE);
207            }
208            return result == IMAPReply.OK;
209        }
210        }
211        return false; // safety check
212    }
213
214    /**
215     * Authenticate to the IMAP server by sending the AUTHENTICATE command with the selected mechanism, using the given user and the given password.
216     *
217     * @param method   the method name
218     * @param user user
219     * @param password password
220     * @return True if successfully completed, false if not.
221     * @throws IOException              If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
222     * @throws NoSuchAlgorithmException If the CRAM hash algorithm cannot be instantiated by the Java runtime system.
223     * @throws InvalidKeyException      If the CRAM hash algorithm failed to use the given password.
224     * @throws InvalidKeySpecException  If the CRAM hash algorithm failed to use the given password.
225     */
226    public boolean authenticate(final AuthenticatingIMAPClient.AUTH_METHOD method, final String user, final String password)
227            throws IOException, NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
228        return auth(method, user, password);
229    }
230
231    /**
232     * 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
233     * this is the ASCII code (and the byte value) of the capital letter 'A'.
234     *
235     * @param a The byte array to convert.
236     * @return The resulting String of hexadecimal codes.
237     */
238    private String convertToHexString(final byte[] a) {
239        final StringBuilder result = new StringBuilder(a.length * 2);
240        for (final byte element : a) {
241            if ((element & 0x0FF) <= 15) {
242                result.append("0");
243            }
244            result.append(Integer.toHexString(element & 0x0FF));
245        }
246        return result.toString();
247    }
248}
249