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.pop3;
19
20 import java.io.BufferedReader;
21 import java.io.BufferedWriter;
22 import java.io.EOFException;
23 import java.io.IOException;
24 import java.io.InputStreamReader;
25 import java.io.OutputStreamWriter;
26 import java.nio.charset.Charset;
27 import java.nio.charset.StandardCharsets;
28 import java.util.ArrayList;
29 import java.util.List;
30
31 import org.apache.commons.net.MalformedServerReplyException;
32 import org.apache.commons.net.ProtocolCommandSupport;
33 import org.apache.commons.net.SocketClient;
34 import org.apache.commons.net.io.CRLFLineReader;
35 import org.apache.commons.net.util.NetConstants;
36
37 /**
38 * The POP3 class is not meant to be used by itself and is provided only so that you may easily implement your own POP3 client if you so desire. If you have no
39 * need to perform your own implementation, you should use {@link org.apache.commons.net.pop3.POP3Client}.
40 * <p>
41 * Rather than list it separately for each method, we mention here that every method communicating with the server and throwing an IOException can also throw a
42 * {@link org.apache.commons.net.MalformedServerReplyException} , which is a subclass of IOException. A MalformedServerReplyException will be thrown when the
43 * reply received from the server deviates enough from the protocol specification that it cannot be interpreted in a useful manner despite attempts to be as
44 * lenient as possible.
45 *
46 *
47 * @see POP3Client
48 * @see org.apache.commons.net.MalformedServerReplyException
49 */
50
51 public class POP3 extends SocketClient {
52 /** The default POP3 port. Set to 110 according to RFC 1288. */
53 public static final int DEFAULT_PORT = 110;
54 /**
55 * A constant representing the state where the client is not yet connected to a POP3 server.
56 */
57 public static final int DISCONNECTED_STATE = -1;
58 /** A constant representing the POP3 authorization state. */
59 public static final int AUTHORIZATION_STATE = 0;
60 /** A constant representing the POP3 transaction state. */
61 public static final int TRANSACTION_STATE = 1;
62 /** A constant representing the POP3 update state. */
63 public static final int UPDATE_STATE = 2;
64
65 static final String OK = "+OK";
66 // The reply indicating intermediate response to a command.
67 static final String OK_INT = "+ ";
68 static final String ERROR = "-ERR";
69
70 // We have to ensure that the protocol communication is in ASCII,
71 // but we use ISO-8859-1 just in case 8-bit characters cross
72 // the wire.
73 static final Charset DEFAULT_ENCODING = StandardCharsets.ISO_8859_1;
74
75 private int popState;
76 BufferedWriter writer;
77
78 BufferedReader reader;
79 int replyCode;
80 String lastReplyLine;
81 List<String> replyLines;
82
83 /**
84 * A ProtocolCommandSupport object used to manage the registering of ProtocolCommandListeners and the firing of ProtocolCommandEvents.
85 */
86 protected ProtocolCommandSupport _commandSupport_;
87
88 /**
89 * The default POP3Client constructor. Initializes the state to <code>DISCONNECTED_STATE</code>.
90 */
91 public POP3() {
92 setDefaultPort(DEFAULT_PORT);
93 popState = DISCONNECTED_STATE;
94 reader = null;
95 writer = null;
96 replyLines = new ArrayList<>();
97 _commandSupport_ = new ProtocolCommandSupport(this);
98 }
99
100 /**
101 * Performs connection initialization and sets state to <code> AUTHORIZATION_STATE </code>.
102 */
103 @Override
104 protected void _connectAction_() throws IOException {
105 super._connectAction_();
106 reader = new CRLFLineReader(new InputStreamReader(_input_, DEFAULT_ENCODING));
107 writer = new BufferedWriter(new OutputStreamWriter(_output_, DEFAULT_ENCODING));
108 getReply();
109 setState(AUTHORIZATION_STATE);
110 }
111
112 /**
113 * Disconnects the client from the server, and sets the state to <code> DISCONNECTED_STATE </code>. The reply text information from the last issued command
114 * is voided to allow garbage collection of the memory used to store that information.
115 *
116 * @throws IOException If there is an error in disconnecting.
117 */
118 @Override
119 public void disconnect() throws IOException {
120 super.disconnect();
121 reader = null;
122 writer = null;
123 lastReplyLine = null;
124 replyLines.clear();
125 setState(DISCONNECTED_STATE);
126 }
127
128 /**
129 * Retrieves the additional lines of a multi-line server reply.
130 *
131 * @throws IOException on error
132 */
133 public void getAdditionalReply() throws IOException {
134 String line;
135
136 line = reader.readLine();
137 while (line != null) {
138 replyLines.add(line);
139 if (line.equals(".")) {
140 break;
141 }
142 line = reader.readLine();
143 }
144 }
145
146 /**
147 * Provide command support to super-class
148 */
149 @Override
150 protected ProtocolCommandSupport getCommandSupport() {
151 return _commandSupport_;
152 }
153
154 private void getReply() throws IOException {
155 final String line;
156
157 replyLines.clear();
158 line = reader.readLine();
159
160 if (line == null) {
161 throw new EOFException("Connection closed without indication.");
162 }
163
164 if (line.startsWith(OK)) {
165 replyCode = POP3Reply.OK;
166 } else if (line.startsWith(ERROR)) {
167 replyCode = POP3Reply.ERROR;
168 } else if (line.startsWith(OK_INT)) {
169 replyCode = POP3Reply.OK_INT;
170 } else {
171 throw new MalformedServerReplyException("Received invalid POP3 protocol response from server." + line);
172 }
173
174 replyLines.add(line);
175 lastReplyLine = line;
176
177 fireReplyReceived(replyCode, getReplyString());
178 }
179
180 /**
181 * Returns the reply to the last command sent to the server. The value is a single string containing all the reply lines including newlines. If the reply is
182 * a single line, but its format ndicates it should be a multiline reply, then you must call {@link #getAdditionalReply getAdditionalReply() } to fetch the
183 * rest of the reply, and then call <code>getReplyString</code> again. You only have to worry about this if you are implementing your own client using the
184 * {@link #sendCommand sendCommand } methods.
185 *
186 * @return The last server response.
187 */
188 public String getReplyString() {
189 final StringBuilder buffer = new StringBuilder(256);
190
191 for (final String entry : replyLines) {
192 buffer.append(entry);
193 buffer.append(SocketClient.NETASCII_EOL);
194 }
195
196 return buffer.toString();
197 }
198
199 /**
200 * Returns an array of lines received as a reply to the last command sent to the server. The lines have end of lines truncated. If the reply is a single
201 * line, but its format ndicates it should be a multiline reply, then you must call {@link #getAdditionalReply getAdditionalReply() } to fetch the rest of
202 * the reply, and then call <code>getReplyStrings</code> again. You only have to worry about this if you are implementing your own client using the
203 * {@link #sendCommand sendCommand } methods.
204 *
205 * @return The last server response.
206 */
207 public String[] getReplyStrings() {
208 return replyLines.toArray(NetConstants.EMPTY_STRING_ARRAY);
209 }
210
211 /**
212 * Returns the current POP3 client state.
213 *
214 * @return The current POP3 client state.
215 */
216 public int getState() {
217 return popState;
218 }
219
220 /**
221 * Removes a ProtocolCommandListener.
222 *
223 * Delegates this incorrectly named method - removeProtocolCommandistener (note the missing "L")- to the correct method
224 * {@link SocketClient#removeProtocolCommandListener}
225 *
226 * @param listener The ProtocolCommandListener to remove
227 */
228 public void removeProtocolCommandistener(final org.apache.commons.net.ProtocolCommandListener listener) {
229 removeProtocolCommandListener(listener);
230 }
231
232 /**
233 * Sends a command with no arguments to the server and returns the reply code.
234 *
235 * @param command The POP3 command to send (one of the POP3Command constants).
236 * @return The server reply code (either {@code POP3Reply.OK}, {@code POP3Reply.ERROR} or {@code POP3Reply.OK_INT}).
237 * @throws IOException on error
238 */
239 public int sendCommand(final int command) throws IOException {
240 return sendCommand(POP3Command.commands[command], null);
241 }
242
243 /**
244 * Sends a command an arguments to the server and returns the reply code.
245 *
246 * @param command The POP3 command to send (one of the POP3Command constants).
247 * @param args The command arguments.
248 * @return The server reply code (either {@code POP3Reply.OK}, {@code POP3Reply.ERROR} or {@code POP3Reply.OK_INT}).
249 * @throws IOException on error
250 */
251 public int sendCommand(final int command, final String args) throws IOException {
252 return sendCommand(POP3Command.commands[command], args);
253 }
254
255 /**
256 * Sends a command with no arguments to the server and returns the reply code.
257 *
258 * @param command The POP3 command to send.
259 * @return The server reply code (either {@code POP3Reply.OK}, {@code POP3Reply.ERROR} or {@code POP3Reply.OK_INT}).
260 * @throws IOException on error
261 */
262 public int sendCommand(final String command) throws IOException {
263 return sendCommand(command, null);
264 }
265
266 /**
267 * Sends a command an arguments to the server and returns the reply code.
268 *
269 * @param command The POP3 command to send.
270 * @param args The command arguments.
271 * @return The server reply code (either {@code POP3Reply.OK}, {@code POP3Reply.ERROR} or {@code POP3Reply.OK_INT}).
272 * @throws IOException on error
273 */
274 public int sendCommand(final String command, final String args) throws IOException {
275 if (writer == null) {
276 throw new IllegalStateException("Socket is not connected");
277 }
278 final StringBuilder __commandBuffer = new StringBuilder();
279 __commandBuffer.append(command);
280
281 if (args != null) {
282 __commandBuffer.append(' ');
283 __commandBuffer.append(args);
284 }
285 __commandBuffer.append(SocketClient.NETASCII_EOL);
286
287 final String message = __commandBuffer.toString();
288 writer.write(message);
289 writer.flush();
290
291 fireCommandSent(command, message);
292
293 getReply();
294 return replyCode;
295 }
296
297 /**
298 * Set the internal POP3 state.
299 *
300 * @param state the new state. This must be one of the <code>_STATE</code> constants.
301 */
302 public void setState(final int state) {
303 popState = state;
304 }
305 }