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 * https://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.smtp;
19
20 import java.io.BufferedWriter;
21 import java.io.IOException;
22 import java.io.InputStreamReader;
23 import java.io.OutputStreamWriter;
24
25 import javax.net.ssl.HostnameVerifier;
26 import javax.net.ssl.KeyManager;
27 import javax.net.ssl.SSLContext;
28 import javax.net.ssl.SSLHandshakeException;
29 import javax.net.ssl.SSLSocket;
30 import javax.net.ssl.SSLSocketFactory;
31 import javax.net.ssl.TrustManager;
32
33 import org.apache.commons.net.io.CRLFLineReader;
34 import org.apache.commons.net.util.SSLContextUtils;
35 import org.apache.commons.net.util.SSLSocketUtils;
36
37 /**
38 * SMTP over SSL processing. Copied from FTPSClient.java and modified to suit SMTP. If implicit mode is selected (NOT the default), SSL/TLS negotiation starts
39 * right after the connection has been established. In explicit mode (the default), SSL/TLS negotiation starts when the user calls execTLS() and the server
40 * accepts the command. Implicit usage:
41 *
42 * <pre>
43 * SMTPSClient c = new SMTPSClient(true);
44 * c.connect("127.0.0.1", 465);
45 * </pre>
46 *
47 * Explicit usage:
48 *
49 * <pre>
50 * SMTPSClient c = new SMTPSClient();
51 * c.connect("127.0.0.1", 25);
52 * if (c.execTLS()) {
53 * // Rest of the commands here
54 * }
55 * </pre>
56 *
57 * <em>Warning</em>: the hostname is not verified against the certificate by default, use {@link #setHostnameVerifier(HostnameVerifier)} or
58 * {@link #setEndpointCheckingEnabled(boolean)} (on Java 1.7+) to enable verification.
59 *
60 * @since 3.0
61 */
62 public class SMTPSClient extends SMTPClient {
63 /** Default secure socket protocol name, like TLS */
64 private static final String DEFAULT_PROTOCOL = "TLS";
65
66 /** The security mode. True - Implicit Mode / False - Explicit Mode. */
67
68 private final boolean isImplicit;
69 /** The secure socket protocol to be used, like SSL/TLS. */
70
71 private final String protocol;
72 /** The context object. */
73
74 private SSLContext context;
75 /**
76 * The cipher suites. SSLSockets have a default set of these anyway, so no initialization required.
77 */
78
79 private String[] suites;
80 /** The protocol versions. */
81
82 private String[] protocols;
83
84 /** The {@link TrustManager} implementation, default null (i.e. use system managers). */
85 private TrustManager trustManager;
86
87 /** The {@link KeyManager}, default null (i.e. use system managers). */
88 private KeyManager keyManager; // seems not to be required
89
90 /** The {@link HostnameVerifier} to use post-TLS, default null (i.e. no verification). */
91 private HostnameVerifier hostnameVerifier;
92
93 /** Use Java 1.7+ HTTPS Endpoint Identification Algorithm. */
94 private boolean tlsEndpointChecking;
95
96 /**
97 * Constructor for SMTPSClient, using {@link #DEFAULT_PROTOCOL} i.e. TLS Sets security mode to explicit (isImplicit = false).
98 */
99 public SMTPSClient() {
100 this(DEFAULT_PROTOCOL, false);
101 }
102
103 /**
104 * Constructor for SMTPSClient, using {@link #DEFAULT_PROTOCOL} i.e. TLS
105 *
106 * @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
107 */
108 public SMTPSClient(final boolean implicit) {
109 this(DEFAULT_PROTOCOL, implicit);
110 }
111
112 /**
113 * Constructor for SMTPSClient, using {@link #DEFAULT_PROTOCOL} i.e. TLS
114 *
115 * @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
116 * @param ctx A pre-configured SSL Context.
117 */
118 public SMTPSClient(final boolean implicit, final SSLContext ctx) {
119 isImplicit = implicit;
120 context = ctx;
121 protocol = DEFAULT_PROTOCOL;
122 }
123
124 /**
125 * Constructor for SMTPSClient.
126 *
127 * @param context A pre-configured SSL Context.
128 * @see #SMTPSClient(boolean, SSLContext)
129 */
130 public SMTPSClient(final SSLContext context) {
131 this(false, context);
132 }
133
134 /**
135 * Constructor for SMTPSClient, using explicit security mode.
136 *
137 * @param proto the protocol.
138 */
139 public SMTPSClient(final String proto) {
140 this(proto, false);
141 }
142
143 /**
144 * Constructor for SMTPSClient.
145 *
146 * @param proto the protocol.
147 * @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
148 */
149 public SMTPSClient(final String proto, final boolean implicit) {
150 protocol = proto;
151 isImplicit = implicit;
152 }
153
154 /**
155 * Constructor for SMTPSClient.
156 *
157 * @param proto the protocol.
158 * @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
159 * @param encoding the encoding
160 * @since 3.3
161 */
162 public SMTPSClient(final String proto, final boolean implicit, final String encoding) {
163 super(encoding);
164 protocol = proto;
165 isImplicit = implicit;
166 }
167
168 /**
169 * Because there are so many connect() methods, the _connectAction_() method is provided as a means of performing some action immediately after establishing
170 * a connection, rather than reimplementing all the connect() methods.
171 *
172 * @throws IOException If it is thrown by _connectAction_().
173 * @see org.apache.commons.net.SocketClient#_connectAction_()
174 */
175 @Override
176 protected void _connectAction_() throws IOException {
177 // Implicit mode.
178 if (isImplicit) {
179 applySocketAttributes();
180 performSSLNegotiation();
181 }
182 super._connectAction_();
183 // Explicit mode - don't do anything. The user calls execTLS()
184 }
185
186 /**
187 * The TLS command execution.
188 *
189 * @throws IOException If an I/O error occurs while sending the command or performing the negotiation.
190 * @return TRUE if the command and negotiation succeeded.
191 */
192 public boolean execTLS() throws IOException {
193 if (!SMTPReply.isPositiveCompletion(sendCommand("STARTTLS"))) {
194 return false;
195 // throw new SSLException(getReplyString());
196 }
197 performSSLNegotiation();
198 return true;
199 }
200
201 /**
202 * Gets the names of the cipher suites which could be enabled for use on this connection. When the underlying {@link java.net.Socket Socket} is not an
203 * {@link SSLSocket} instance, returns null.
204 *
205 * @return An array of cipher suite names, or {@code null}.
206 */
207 public String[] getEnabledCipherSuites() {
208 if (_socket_ instanceof SSLSocket) {
209 return ((SSLSocket) _socket_).getEnabledCipherSuites();
210 }
211 return null;
212 }
213
214 /**
215 * Gets the names of the protocol versions which are currently enabled for use on this connection. When the underlying {@link java.net.Socket Socket} is
216 * not an {@link SSLSocket} instance, returns null.
217 *
218 * @return An array of protocols, or {@code null}.
219 */
220 public String[] getEnabledProtocols() {
221 if (_socket_ instanceof SSLSocket) {
222 return ((SSLSocket) _socket_).getEnabledProtocols();
223 }
224 return null;
225 }
226
227 /**
228 * Gets the currently configured {@link HostnameVerifier}.
229 *
230 * @return A HostnameVerifier instance.
231 * @since 3.4
232 */
233 public HostnameVerifier getHostnameVerifier() {
234 return hostnameVerifier;
235 }
236
237 /**
238 * Gets the {@link KeyManager} instance.
239 *
240 * @return The current {@link KeyManager} instance.
241 */
242 public KeyManager getKeyManager() {
243 return keyManager;
244 }
245
246 /**
247 * Gets the currently configured {@link TrustManager}.
248 *
249 * @return A TrustManager instance.
250 */
251 public TrustManager getTrustManager() {
252 return trustManager;
253 }
254
255 /**
256 * Performs a lazy init of the SSL context.
257 *
258 * @throws IOException When could not initialize the SSL context.
259 */
260 private void initSSLContext() throws IOException {
261 if (context == null) {
262 context = SSLContextUtils.createSSLContext(protocol, getKeyManager(), getTrustManager());
263 }
264 }
265
266 /**
267 * Tests whether or not endpoint identification using the HTTPS algorithm on Java 1.7+ is enabled. The default behavior is for this to be disabled.
268 *
269 * @return True if enabled, false if not.
270 * @since 3.4
271 */
272 public boolean isEndpointCheckingEnabled() {
273 return tlsEndpointChecking;
274 }
275
276 /**
277 * SSL/TLS negotiation. Acquires an SSL socket of a connection and carries out handshake processing.
278 *
279 * @throws IOException If server negotiation fails.
280 */
281 private void performSSLNegotiation() throws IOException {
282 initSSLContext();
283
284 final SSLSocketFactory ssf = context.getSocketFactory();
285 final String host = _hostname_ != null ? _hostname_ : getRemoteAddress().getHostAddress();
286 final int port = getRemotePort();
287 final SSLSocket socket = (SSLSocket) ssf.createSocket(_socket_, host, port, true);
288 socket.setEnableSessionCreation(true);
289 socket.setUseClientMode(true);
290
291 if (tlsEndpointChecking) {
292 SSLSocketUtils.enableEndpointNameVerification(socket);
293 }
294 if (protocols != null) {
295 socket.setEnabledProtocols(protocols);
296 }
297 if (suites != null) {
298 socket.setEnabledCipherSuites(suites);
299 }
300 socket.startHandshake();
301
302 // TODO the following setup appears to duplicate that in the super class methods
303 _socket_ = socket;
304 _input_ = socket.getInputStream();
305 _output_ = socket.getOutputStream();
306 reader = new CRLFLineReader(new InputStreamReader(_input_, encoding));
307 writer = new BufferedWriter(new OutputStreamWriter(_output_, encoding));
308
309 if (hostnameVerifier != null && !hostnameVerifier.verify(host, socket.getSession())) {
310 throw new SSLHandshakeException("Hostname doesn't match certificate");
311 }
312 }
313
314 /**
315 * Sets which particular cipher suites are enabled for use on this connection. Called before server negotiation.
316 *
317 * @param cipherSuites The cipher suites.
318 */
319 public void setEnabledCipherSuites(final String[] cipherSuites) {
320 suites = cipherSuites.clone();
321 }
322
323 /**
324 * Sets which particular protocol versions are enabled for use on this connection. I perform setting before a server negotiation.
325 *
326 * @param protocolVersions The protocol versions.
327 */
328 public void setEnabledProtocols(final String[] protocolVersions) {
329 protocols = protocolVersions.clone();
330 }
331
332 /**
333 * Sets automatic endpoint identification checking using the HTTPS algorithm is supported on Java 1.7+. The default behavior is for this to be disabled.
334 *
335 * @param enable Enable automatic endpoint identification checking using the HTTPS algorithm on Java 1.7+.
336 * @since 3.4
337 */
338 public void setEndpointCheckingEnabled(final boolean enable) {
339 tlsEndpointChecking = enable;
340 }
341
342 /**
343 * Sets to override the default {@link HostnameVerifier} to use.
344 *
345 * @param newHostnameVerifier The HostnameVerifier implementation to set or {@code null} to disable.
346 * @since 3.4
347 */
348 public void setHostnameVerifier(final HostnameVerifier newHostnameVerifier) {
349 hostnameVerifier = newHostnameVerifier;
350 }
351
352 /**
353 * Sets a {@link KeyManager} to use.
354 *
355 * @param newKeyManager The KeyManager implementation to set.
356 * @see org.apache.commons.net.util.KeyManagerUtils
357 */
358 public void setKeyManager(final KeyManager newKeyManager) {
359 keyManager = newKeyManager;
360 }
361
362 /**
363 * Override the default {@link TrustManager} to use.
364 *
365 * @param newTrustManager The TrustManager implementation to set.
366 * @see org.apache.commons.net.util.TrustManagerUtils
367 */
368 public void setTrustManager(final TrustManager newTrustManager) {
369 trustManager = newTrustManager;
370 }
371 }
372