POP3Client.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.net.pop3;
import java.io.IOException;
import java.io.Reader;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.ListIterator;
import java.util.StringTokenizer;
import org.apache.commons.net.io.DotTerminatedMessageReader;
/**
* The POP3Client class implements the client side of the Internet POP3 Protocol defined in RFC 1939. All commands are supported, including the APOP command
* which requires MD5 encryption. See RFC 1939 for more details on the POP3 protocol.
* <p>
* 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
* {@link org.apache.commons.net.MalformedServerReplyException} , which is a subclass of IOException. A MalformedServerReplyException will be thrown when the
* 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
* lenient as possible.
*
*
* @see POP3MessageInfo
* @see org.apache.commons.net.io.DotTerminatedMessageReader
* @see org.apache.commons.net.MalformedServerReplyException
*/
public class POP3Client extends POP3 {
private static POP3MessageInfo parseStatus(final String line) {
int num, size;
final StringTokenizer tokenizer;
tokenizer = new StringTokenizer(line);
if (!tokenizer.hasMoreElements()) {
return null;
}
num = size = 0;
try {
num = Integer.parseInt(tokenizer.nextToken());
if (!tokenizer.hasMoreElements()) {
return null;
}
size = Integer.parseInt(tokenizer.nextToken());
} catch (final NumberFormatException e) {
return null;
}
return new POP3MessageInfo(num, size);
}
private static POP3MessageInfo parseUID(String line) {
int num;
final StringTokenizer tokenizer;
tokenizer = new StringTokenizer(line);
if (!tokenizer.hasMoreElements()) {
return null;
}
num = 0;
try {
num = Integer.parseInt(tokenizer.nextToken());
if (!tokenizer.hasMoreElements()) {
return null;
}
line = tokenizer.nextToken();
} catch (final NumberFormatException e) {
return null;
}
return new POP3MessageInfo(num, line);
}
/**
* Send a CAPA command to the POP3 server.
*
* @return True if the command was successful, false if not.
* @throws IOException If a network I/O error occurs in the process of sending the CAPA command.
* @since 3.1 (was previously in ExtendedPOP3Client)
*/
public boolean capa() throws IOException {
if (sendCommand(POP3Command.CAPA) == POP3Reply.OK) {
getAdditionalReply();
return true;
}
return false;
}
/**
* Delete a message from the POP3 server. The message is only marked for deletion by the server. If you decide to unmark the message, you must issue a
* {@link #reset reset } command. Messages marked for deletion are only deleted by the server on {@link #logout logout }.
* A deletion attempt can only succeed if the client is in the {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE } .
*
* @param messageId The message number to delete.
* @return True if the deletion attempt was successful, false if not.
* @throws IOException If a network I/O error occurs in the process of sending the delete command.
*/
public boolean deleteMessage(final int messageId) throws IOException {
if (getState() == TRANSACTION_STATE) {
return sendCommand(POP3Command.DELE, Integer.toString(messageId)) == POP3Reply.OK;
}
return false;
}
/**
* List an individual message. A list attempt can only succeed if the client is in the {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE
* TRANSACTION_STATE } . Returns a POP3MessageInfo instance containing the number of the listed message and the size of the message in bytes. Returns null
* if the list attempt fails (e.g., if the specified message number does not exist).
*
* @param messageId The number of the message list.
* @return A POP3MessageInfo instance containing the number of the listed message and the size of the message in bytes. Returns null if the list attempt
* fails.
* @throws IOException If a network I/O error occurs in the process of sending the list command.
*/
public POP3MessageInfo listMessage(final int messageId) throws IOException {
if (getState() != TRANSACTION_STATE) {
return null;
}
if (sendCommand(POP3Command.LIST, Integer.toString(messageId)) != POP3Reply.OK) {
return null;
}
return parseStatus(lastReplyLine.substring(3));
}
/**
* List all messages. A list attempt can only succeed if the client is in the {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
* . Returns an array of POP3MessageInfo instances, each containing the number of a message and its size in bytes. If there are no messages, this method
* returns a zero length array. If the list attempt fails, it returns null.
*
* @return An array of POP3MessageInfo instances representing all messages in the order they appear in the mailbox, each containing the number of a message
* and its size in bytes. If there are no messages, this method returns a zero length array. If the list attempt fails, it returns null.
* @throws IOException If a network I/O error occurs in the process of sending the list command.
*/
public POP3MessageInfo[] listMessages() throws IOException {
if (getState() != TRANSACTION_STATE) {
return null;
}
if (sendCommand(POP3Command.LIST) != POP3Reply.OK) {
return null;
}
getAdditionalReply();
// This could be a zero length array if no messages present
final POP3MessageInfo[] messages = new POP3MessageInfo[replyLines.size() - 2]; // skip first and last lines
final ListIterator<String> en = replyLines.listIterator(1); // Skip first line
// Fetch lines.
Arrays.setAll(messages, i -> parseStatus(en.next()));
return messages;
}
/**
* List the unique identifier for a message. A list attempt can only succeed if the client is in the
* {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE } . Returns a POP3MessageInfo instance containing the number of the listed
* message and the unique identifier for that message. Returns null if the list attempt fails (e.g., if the specified message number does not exist).
*
* @param messageId The number of the message list.
* @return A POP3MessageInfo instance containing the number of the listed message and the unique identifier for that message. Returns null if the list
* attempt fails.
* @throws IOException If a network I/O error occurs in the process of sending the list unique identifier command.
*/
public POP3MessageInfo listUniqueIdentifier(final int messageId) throws IOException {
if (getState() != TRANSACTION_STATE) {
return null;
}
if (sendCommand(POP3Command.UIDL, Integer.toString(messageId)) != POP3Reply.OK) {
return null;
}
return parseUID(lastReplyLine.substring(3));
}
/**
* List the unique identifiers for all messages. A list attempt can only succeed if the client is in the
* {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE } . Returns an array of POP3MessageInfo instances, each containing the number
* of a message and its unique identifier. If there are no messages, this method returns a zero length array. If the list attempt fails, it returns null.
*
* @return An array of POP3MessageInfo instances representing all messages in the order they appear in the mailbox, each containing the number of a message
* and its unique identifier If there are no messages, this method returns a zero length array. If the list attempt fails, it returns null.
* @throws IOException If a network I/O error occurs in the process of sending the list unique identifier command.
*/
public POP3MessageInfo[] listUniqueIdentifiers() throws IOException {
if (getState() != TRANSACTION_STATE) {
return null;
}
if (sendCommand(POP3Command.UIDL) != POP3Reply.OK) {
return null;
}
getAdditionalReply();
// This could be a zero length array if no messages present
final POP3MessageInfo[] messages = new POP3MessageInfo[replyLines.size() - 2]; // skip first and last lines
final ListIterator<String> en = replyLines.listIterator(1); // skip first line
// Fetch lines.
Arrays.setAll(messages, i -> parseUID(en.next()));
return messages;
}
/**
* Login to the POP3 server with the given user and password. You must first connect to the server with
* {@link org.apache.commons.net.SocketClient#connect connect } before attempting to log in. A login attempt is only valid if the client is in the
* {@link org.apache.commons.net.pop3.POP3#AUTHORIZATION_STATE AUTHORIZATION_STATE }. After logging in, the client enters the
* {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }.
*
* @param user The account name being logged in to.
* @param password The plain text password of the account.
* @return True if the login attempt was successful, false if not.
* @throws IOException If a network I/O error occurs in the process of logging in.
*/
public boolean login(final String user, final String password) throws IOException {
if (getState() != AUTHORIZATION_STATE) {
return false;
}
if (sendCommand(POP3Command.USER, user) != POP3Reply.OK) {
return false;
}
if (sendCommand(POP3Command.PASS, password) != POP3Reply.OK) {
return false;
}
setState(TRANSACTION_STATE);
return true;
}
/**
* Login to the POP3 server with the given username and authentication information. Use this method when connecting to a server requiring authentication
* using the APOP command. Because the timestamp produced in the greeting banner varies from server to server, it is not possible to consistently extract
* the information. Therefore, after connecting to the server, you must call {@link org.apache.commons.net.pop3.POP3#getReplyString getReplyString } and
* parse out the timestamp information yourself.
* <p>
* You must first connect to the server with {@link org.apache.commons.net.SocketClient#connect connect } before attempting to log in. A login attempt is
* only valid if the client is in the {@link org.apache.commons.net.pop3.POP3#AUTHORIZATION_STATE AUTHORIZATION_STATE }. After logging in, the client
* enters the {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }. After connecting, you must parse out the server specific
* information to use as a timestamp, and pass that information to this method. The secret is a shared secret known to you and the server. See RFC 1939 for
* more details regarding the APOP command.
*
* @param user The account name being logged in to.
* @param timestamp The timestamp string to combine with the secret.
* @param secret The shared secret which produces the MD5 digest when combined with the timestamp.
* @return True if the login attempt was successful, false if not.
* @throws IOException If a network I/O error occurs in the process of logging in.
* @throws NoSuchAlgorithmException If the MD5 encryption algorithm cannot be instantiated by the Java runtime system.
*/
public boolean login(final String user, String timestamp, final String secret) throws IOException, NoSuchAlgorithmException {
int i;
final byte[] digest;
final StringBuilder buffer;
final StringBuilder digestBuffer;
final MessageDigest md5;
if (getState() != AUTHORIZATION_STATE) {
return false;
}
md5 = MessageDigest.getInstance("MD5");
timestamp += secret;
digest = md5.digest(timestamp.getBytes(getCharset()));
digestBuffer = new StringBuilder(128);
for (i = 0; i < digest.length; i++) {
final int digit = digest[i] & 0xff;
if (digit <= 15) { // Add leading zero if necessary (NET-351)
digestBuffer.append("0");
}
digestBuffer.append(Integer.toHexString(digit));
}
buffer = new StringBuilder(256);
buffer.append(user);
buffer.append(' ');
buffer.append(digestBuffer.toString());
if (sendCommand(POP3Command.APOP, buffer.toString()) != POP3Reply.OK) {
return false;
}
setState(TRANSACTION_STATE);
return true;
}
/**
* Logout of the POP3 server. To fully disconnect from the server you must call {@link org.apache.commons.net.pop3.POP3#disconnect disconnect }. A logout
* attempt is valid in any state. If the client is in the {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE } , it enters the
* {@link org.apache.commons.net.pop3.POP3#UPDATE_STATE UPDATE_STATE } on a successful logout.
*
* @return True if the logout attempt was successful, false if not.
* @throws IOException If a network I/O error occurs in the process of logging out.
*/
public boolean logout() throws IOException {
if (getState() == TRANSACTION_STATE) {
setState(UPDATE_STATE);
}
sendCommand(POP3Command.QUIT);
return replyCode == POP3Reply.OK;
}
/**
* Send a NOOP command to the POP3 server. This is useful for keeping a connection alive since most POP3 servers will time out after 10 minutes of
* inactivity. A noop attempt will only succeed if the client is in the {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE } .
*
* @return True if the noop attempt was successful, false if not.
* @throws IOException If a network I/O error occurs in the process of sending the NOOP command.
*/
public boolean noop() throws IOException {
if (getState() == TRANSACTION_STATE) {
return sendCommand(POP3Command.NOOP) == POP3Reply.OK;
}
return false;
}
/**
* Reset the POP3 session. This is useful for undoing any message deletions that may have been performed. A reset attempt can only succeed if the client is
* in the {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE } .
*
* @return True if the reset attempt was successful, false if not.
* @throws IOException If a network I/O error occurs in the process of sending the reset command.
*/
public boolean reset() throws IOException {
if (getState() == TRANSACTION_STATE) {
return sendCommand(POP3Command.RSET) == POP3Reply.OK;
}
return false;
}
/**
* Retrieve a message from the POP3 server. A retrieve message attempt can only succeed if the client is in the
* {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
* <p>
* You must not issue any commands to the POP3 server (i.e., call any other methods) until you finish reading the message from the returned BufferedReader
* instance. The POP3 protocol uses the same stream for issuing commands as it does for returning results. Therefore, the returned BufferedReader actually
* reads directly from the POP3 connection. After the end of message has been reached, new commands can be executed and their replies read. If you do not
* follow these requirements, your program will not work properly.
*
* @param messageId The number of the message to fetch.
* @return A DotTerminatedMessageReader instance from which the entire message can be read. This can safely be cast to a {@link java.io.BufferedReader
* BufferedReader} in order to use the {@link java.io.BufferedReader#readLine() BufferedReader#readLine()} method. Returns null if the retrieval
* attempt fails (e.g., if the specified message number does not exist).
* @throws IOException If a network I/O error occurs in the process of sending the retrieve message command.
*/
public Reader retrieveMessage(final int messageId) throws IOException {
if (getState() != TRANSACTION_STATE) {
return null;
}
if (sendCommand(POP3Command.RETR, Integer.toString(messageId)) != POP3Reply.OK) {
return null;
}
return new DotTerminatedMessageReader(reader);
}
/**
* Retrieve only the specified top number of lines of a message from the POP3 server. A retrieve top lines attempt can only succeed if the client is in the
* {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
* <p>
* You must not issue any commands to the POP3 server (i.e., call any other methods) until you finish reading the message from the returned BufferedReader
* instance. The POP3 protocol uses the same stream for issuing commands as it does for returning results. Therefore, the returned BufferedReader
* actually reads directly from the POP3 connection. After the end of message has been reached, new commands can be executed and their replies read.
* If you do not follow these requirements, your program will not work properly.
*
* @param messageId The number of the message to fetch.
* @param numLines The top number of lines to fetch. This must be >= 0.
* @return A DotTerminatedMessageReader instance from which the specified top number of lines of the message can be read. This can safely be cast to a
* {@link java.io.BufferedReader BufferedReader} in order to use the {@link java.io.BufferedReader#readLine() BufferedReader#readLine()} method.
* Returns null if the retrieval attempt fails (e.g., if the specified message number does not exist).
* @throws IOException If a network I/O error occurs in the process of sending the top command.
*/
public Reader retrieveMessageTop(final int messageId, final int numLines) throws IOException {
if (numLines < 0 || getState() != TRANSACTION_STATE) {
return null;
}
if (sendCommand(POP3Command.TOP, Integer.toString(messageId) + " " + Integer.toString(numLines)) != POP3Reply.OK) {
return null;
}
return new DotTerminatedMessageReader(reader);
}
/**
* Get the mailbox status. A status attempt can only succeed if the client is in the {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE
* TRANSACTION_STATE } . Returns a POP3MessageInfo instance containing the number of messages in the mailbox and the total size of the messages in bytes.
* Returns null if the status the attempt fails.
*
* @return A POP3MessageInfo instance containing the number of messages in the mailbox and the total size of the messages in bytes. Returns null if the
* status the attempt fails.
* @throws IOException If a network I/O error occurs in the process of sending the status command.
*/
public POP3MessageInfo status() throws IOException {
if (getState() != TRANSACTION_STATE) {
return null;
}
if (sendCommand(POP3Command.STAT) != POP3Reply.OK) {
return null;
}
return parseStatus(lastReplyLine.substring(3));
}
}