pop3handler.java

java 开发的邮件服务器平台。支持以下协议。 协议可以修改为自己的专门标识

/***********************************************************************
 * Copyright (c) 2000-2004 The Apache Software Foundation.             *
 * All rights reserved.                                                *
 * ------------------------------------------------------------------- *
 * 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.james.pop3server;

import org.apache.avalon.cornerstone.services.connection.ConnectionHandler;
import org.apache.avalon.excalibur.collections.ListUtils;
import org.apache.avalon.excalibur.pool.Poolable;
import org.apache.avalon.framework.activity.Disposable;
import org.apache.avalon.framework.logger.AbstractLogEnabled;

import org.apache.james.Constants;
import org.apache.james.core.MailImpl;
import org.apache.james.services.MailRepository;
import org.apache.james.services.MailServer;
import org.apache.james.services.UsersRepository;
import org.apache.james.services.UsersStore;
import org.apache.james.util.CRLFTerminatedReader;
import org.apache.james.util.ExtraDotOutputStream;
import org.apache.james.util.InternetPrintWriter;
import org.apache.james.util.watchdog.BytesWrittenResetOutputStream;
import org.apache.james.util.watchdog.Watchdog;
import org.apache.james.util.watchdog.WatchdogTarget;
import org.apache.mailet.Mail;

import javax.mail.MessagingException;
import java.io.*;
import java.net.Socket;
import java.util.*;

/**
 * The handler class for POP3 connections.
 *
 */
public class POP3Handler
    extends AbstractLogEnabled
    implements ConnectionHandler, Poolable {

    // POP3 Server identification string used in POP3 headers
    private static final String softwaretype        = "JAMES POP3 Server "
                                                        + Constants.SOFTWARE_VERSION;

    // POP3 response prefixes
    private final static String OK_RESPONSE = "+OK";    // OK response.  Requested content
                                                        // will follow

    private final static String ERR_RESPONSE = "-ERR";  // Error response.  Requested content
                                                        // will not be provided.  This prefix
                                                        // is followed by a more detailed
                                                        // error message

    // Authentication states for the POP3 interaction

    private final static int AUTHENTICATION_READY = 0;    // Waiting for user id

    private final static int AUTHENTICATION_USERSET = 1;  // User id provided, waiting for
                                                          // password

    private final static int TRANSACTION = 2;             // A valid user id/password combination
                                                          // has been provided.  In this state
                                                          // the client can access the mailbox
                                                          // of the specified user

    private static final Mail DELETED = new MailImpl();   // A placeholder for emails deleted
                                                          // during the course of the POP3
                                                          // transaction.  This Mail instance
                                                          // is used to enable fast checks as
                                                          // to whether an email has been
                                                          // deleted from the inbox.

    /**
     * The per-service configuration data that applies to all handlers
     */
    private POP3HandlerConfigurationData theConfigData;

    /**
     * The mail server's copy of the user's inbox
     */
    private MailRepository userInbox;

    /**
     * The thread executing this handler
     */
    private Thread handlerThread;

    /**
     * The TCP/IP socket over which the POP3 interaction
     * is occurring
     */
    private Socket socket;

    /**
     * The reader associated with incoming characters.
     */
    private BufferedReader in;

    /**
     * The writer to which outgoing messages are written.
     */
    private PrintWriter out;

    /**
     * The socket's output stream
     */
    private OutputStream outs;

    /**
     * The current transaction state of the handler
     */
    private int state;

    /**
     * The user id associated with the POP3 dialogue
     */
    private String user;

    /**
     * A dynamic list representing the set of
     * emails in the user's inbox at any given time
     * during the POP3 transaction.
     */
    private ArrayList userMailbox = new ArrayList();

    private ArrayList backupUserMailbox;         // A snapshot list representing the set of
                                                 // emails in the user's inbox at the beginning
                                                 // of the transaction

    /**
     * The watchdog being used by this handler to deal with idle timeouts.
     */
    private Watchdog theWatchdog;

    /**
     * The watchdog target that idles out this handler.
     */
    private WatchdogTarget theWatchdogTarget = new POP3WatchdogTarget();

    /**
     * Set the configuration data for the handler.
     *
     * @param theData the configuration data
     */
    void setConfigurationData(POP3HandlerConfigurationData theData) {
        theConfigData = theData;
    }

    /**
     * Set the Watchdog for use by this handler.
     *
     * @param theWatchdog the watchdog
     */
    void setWatchdog(Watchdog theWatchdog) {
        this.theWatchdog = theWatchdog;
    }

    /**
     * Gets the Watchdog Target that should be used by Watchdogs managing
     * this connection.
     *
     * @return the WatchdogTarget
     */
    WatchdogTarget getWatchdogTarget() {
        return theWatchdogTarget;
    }

    /**
     * Idle out this connection
     */
    void idleClose() {
        if (getLogger() != null) {
            getLogger().error("POP3 Connection has idled out.");
        }
        try {
            if (socket != null) {
                socket.close();
            }
        } catch (Exception e) {
            // ignored
        } finally {
            socket = null;
        }

        synchronized (this) {
            // Interrupt the thread to recover from internal hangs
            if (handlerThread != null) {
                handlerThread.interrupt();
                handlerThread = null;
            }
        }

    }

    /**
     * @see org.apache.avalon.cornerstone.services.connection.ConnectionHandler#handleConnection(Socket)
     */
    public void handleConnection( Socket connection )
            throws IOException {

        String remoteHost = "";
        String remoteIP = "";

        try {
            this.socket = connection;
            synchronized (this) {
                handlerThread = Thread.currentThread();
            }
            // in = new BufferedReader(new InputStreamReader(socket.getInputStream(), "ASCII"), 512);
            in = new CRLFTerminatedReader(new BufferedInputStream(socket.getInputStream(), 512), "ASCII");
            remoteIP = socket.getInetAddress().getHostAddress ();
            remoteHost = socket.getInetAddress().getHostName ();
        } catch (Exception e) {
            if (getLogger().isErrorEnabled()) {
                StringBuffer exceptionBuffer =
                    new StringBuffer(256)
                            .append("Cannot open connection from ")
                            .append(remoteHost)
                            .append(" (")
                            .append(remoteIP)
                            .append("): ")
                            .append(e.getMessage());
                getLogger().error( exceptionBuffer.toString(), e );
            }
        }

        if (getLogger().isInfoEnabled()) {
            StringBuffer logBuffer =
                new StringBuffer(128)
                        .append("Connection from ")
                        .append(remoteHost)
                        .append(" (")
                        .append(remoteIP)
                        .append(") ");
            getLogger().info(logBuffer.toString());
        }

        try {
            outs = new BufferedOutputStream(socket.getOutputStream(), 1024);
            out = new InternetPrintWriter(outs, true);
            state = AUTHENTICATION_READY;
            user = "unknown";
            StringBuffer responseBuffer =
                new StringBuffer(256)
                        .append(OK_RESPONSE)
                        .append(" ")
                        .append(theConfigData.getHelloName())
                        .append(" POP3 server (")
                        .append(POP3Handler.softwaretype)
                        .append(") ready ");
            out.println(responseBuffer.toString());

            theWatchdog.start();
            while (parseCommand(readCommandLine())) {
                theWatchdog.reset();
            }
            theWatchdog.stop();
            if (getLogger().isInfoEnabled()) {
                StringBuffer logBuffer =
                    new StringBuffer(128)
                        .append("Connection for ")
                        .append(user)
                        .append(" from ")
                        .append(remoteHost)
                        .append(" (")
                        .append(remoteIP)
                        .append(") closed.");
                getLogger().info(logBuffer.toString());
            }
        } catch (Exception e) {
            out.println(ERR_RESPONSE + " Error closing connection.");
            out.flush();
            StringBuffer exceptionBuffer =
                new StringBuffer(128)
                        .append("Exception during connection from ")
                        .append(remoteHost)
                        .append(" (")
                        .append(remoteIP)
                        .append(") : ")
                        .append(e.getMessage());
            getLogger().error(exceptionBuffer.toString(), e );
        } finally {
            resetHandler();
        }
    }

    /**
     * Resets the handler data to a basic state.
     */
    private void resetHandler() {

        if (theWatchdog != null) {
            if (theWatchdog instanceof Disposable) {
                ((Disposable)theWatchdog).dispose();
            }
            theWatchdog = null;
        }

        // Close and clear streams, sockets

        try {
            if (socket != null) {
                socket.close();
                socket = null;
            }
        } catch (IOException ioe) {
            // Ignoring exception on close
        } finally {
            socket = null;
        }

        try {
            if (in != null) {
                in.close();
            }
        } catch (Exception e) {
            // Ignored
        } finally {
            in = null;
        }

        try {
            if (out != null) {
                out.close();
            }
        } catch (Exception e) {
            // Ignored
        } finally {
            out = null;
        }

        try {
           if (outs != null) {
               outs.close();
            }
        } catch (Exception e) {
            // Ignored
        } finally {
            outs = null;
        }

        synchronized (this) {
            handlerThread = null;
        }

        // Clear user data
        user = null;
        userInbox = null;
        if (userMailbox != null) {
            userMailbox.clear();
            userMailbox = null;
        }

        if (backupUserMailbox != null) {
            backupUserMailbox.clear();
            backupUserMailbox = null;
        }