1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.net.imap;
19
20 import java.io.IOException;
21 import java.security.InvalidKeyException;
22 import java.security.NoSuchAlgorithmException;
23 import java.security.spec.InvalidKeySpecException;
24 import java.util.Base64;
25
26 import javax.crypto.Mac;
27 import javax.crypto.spec.SecretKeySpec;
28 import javax.net.ssl.SSLContext;
29
30 /**
31 * An IMAP Client class with authentication support.
32 *
33 * @see IMAPSClient
34 */
35 public class AuthenticatingIMAPClient extends IMAPSClient {
36
37 /** {@link Mac} algorithm. */
38 private static final String MAC_ALGORITHM = "HmacMD5";
39
40 /**
41 * The enumeration of currently-supported authentication methods.
42 */
43 public enum AUTH_METHOD {
44
45 /** The standardized (RFC4616) PLAIN method, which sends the password unencrypted (insecure). */
46
47 PLAIN("PLAIN"),
48 /** The standardized (RFC2195) CRAM-MD5 method, which doesn't send the password (secure). */
49
50 CRAM_MD5("CRAM-MD5"),
51
52 /** The standardized Microsoft LOGIN method, which sends the password unencrypted (insecure). */
53 LOGIN("LOGIN"),
54
55 /** XOAUTH */
56 XOAUTH("XOAUTH"),
57
58 /** XOAUTH 2 */
59 XOAUTH2("XOAUTH2");
60
61 private final String authName;
62
63 AUTH_METHOD(final String name) {
64 this.authName = name;
65 }
66
67 /**
68 * Gets the name of the given authentication method suitable for the server.
69 *
70 * @return The name of the given authentication method suitable for the server.
71 */
72 public final String getAuthName() {
73 return authName;
74 }
75 }
76
77 /**
78 * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient. Sets security mode to explicit (isImplicit = false).
79 */
80 public AuthenticatingIMAPClient() {
81 this(DEFAULT_PROTOCOL, false);
82 }
83
84 /**
85 * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
86 *
87 * @param implicit The security mode (Implicit/Explicit).
88 */
89 public AuthenticatingIMAPClient(final boolean implicit) {
90 this(DEFAULT_PROTOCOL, implicit);
91 }
92
93 /**
94 * Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
95 *
96 * @param implicit The security mode(Implicit/Explicit).
97 * @param ctx A pre-configured SSL Context.
98 */
99 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 hex values of the bytes. For example, the byte 'A' will be converted to '41', because this is
233 * 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 hex 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