pop3client.java

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/*
 * Copyright 2001-2005 The Apache Software Foundation
 *
 * Licensed 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.Enumeration;
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.
 * <p>
 * <p>
 * @author Daniel F. Savarese
 * @see POP3MessageInfo
 * @see org.apache.commons.net.io.DotTerminatedMessageReader
 * @see org.apache.commons.net.MalformedServerReplyException
 ***/

public class POP3Client extends POP3
{

    private static POP3MessageInfo __parseStatus(String line)
    {
        int num, size;
        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 (NumberFormatException e)
        {
            return null;
        }

        return new POP3MessageInfo(num, size);
    }

    private static POP3MessageInfo __parseUID(String line)
    {
        int num;
        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 (NumberFormatException e)
        {
            return null;
        }

        return new POP3MessageInfo(num, line);
    }

    /***
     * Login to the POP3 server with the given username and password.  You
     * must first connect to the server with
     * {@link org.apache.commons.net.SocketClient#connect  connect }
     * before attempting to login.  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 }
     * .
     * <p>
     * @param username  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.
     * @exception IOException If a network I/O error occurs in the process of
     *            logging in.
     ***/
    public boolean login(String username, String password) throws IOException
    {
        if (getState() != AUTHORIZATION_STATE)
            return false;

        if (sendCommand(POP3Command.USER, username) != 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 login.  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.
     * <p>
     * @param username  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.
     * @exception IOException If a network I/O error occurs in the process of
     *            logging in.
     * @exception NoSuchAlgorithmException If the MD5 encryption algorithm
     *      cannot be instantiated by the Java runtime system.
     ***/
    public boolean login(String username, String timestamp, String secret)
    throws IOException, NoSuchAlgorithmException
    {
        int i;
        byte[] digest;
        StringBuffer buffer, digestBuffer;
        MessageDigest md5;

        if (getState() != AUTHORIZATION_STATE)
            return false;

        md5 = MessageDigest.getInstance("MD5");
        timestamp += secret;
        digest = md5.digest(timestamp.getBytes());
        digestBuffer = new StringBuffer(128);

        for (i = 0; i < digest.length; i++)
            digestBuffer.append(Integer.toHexString(digest[i] & 0xff));

        buffer = new StringBuffer(256);
        buffer.append(username);
        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.
     * <p>
     * @return True if the logout attempt was successful, false if not.
     * @exception 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 timeout 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 }
     * .
     * <p>
     * @return True if the noop attempt was successful, false if not.
     * @exception 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;
    }


    /***
     * 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 issuse a {@link #reset  reset } command.  Messages marked
     * for deletion are only deleted by the server on
     * {@link #logout  logout }.
     * A delete attempt can only succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .
     * <p>
     * @param messageId  The message number to delete.
     * @return True if the deletion attempt was successful, false if not.
     * @exception IOException If a network I/O error occurs in the process of
     *           sending the delete command.
     ***/
    public boolean deleteMessage(int messageId) throws IOException
    {
        if (getState() == TRANSACTION_STATE)
            return (sendCommand(POP3Command.DELE, Integer.toString(messageId))
                    == POP3Reply.OK);
        return false;
    }