mitm.application.djigzo.james.smtpserver.CheckRepositoriesBlockingRcptCmdHandler.java Source code

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/*
 * Copyright (c) 2008-2011, Martijn Brinkers, Djigzo.
 * 
 * This file is part of Djigzo email encryption.
 *
 * Djigzo is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License 
 * version 3, 19 November 2007 as published by the Free Software 
 * Foundation.
 *
 * Djigzo is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public 
 * License along with Djigzo. If not, see <http://www.gnu.org/licenses/>
 *
 * Additional permission under GNU AGPL version 3 section 7
 * 
 * If you modify this Program, or any covered work, by linking or 
 * combining it with aspectjrt.jar, aspectjweaver.jar, tyrex-1.0.3.jar, 
 * freemarker.jar, dom4j.jar, mx4j-jmx.jar, mx4j-tools.jar, 
 * spice-classman-1.0.jar, spice-loggerstore-0.5.jar, spice-salt-0.8.jar, 
 * spice-xmlpolicy-1.0.jar, saaj-api-1.3.jar, saaj-impl-1.3.jar, 
 * wsdl4j-1.6.1.jar (or modified versions of these libraries), 
 * containing parts covered by the terms of Eclipse Public License, 
 * tyrex license, freemarker license, dom4j license, mx4j license,
 * Spice Software License, Common Development and Distribution License
 * (CDDL), Common Public License (CPL) the licensors of this Program grant 
 * you additional permission to convey the resulting work.
 */
package mitm.application.djigzo.james.smtpserver;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;

import javax.mail.MessagingException;

import mitm.application.djigzo.james.JamesStoreManager;
import mitm.application.djigzo.service.SystemServices;

import org.apache.avalon.framework.configuration.Configurable;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.commons.lang.text.StrBuilder;
import org.apache.james.services.MailRepository;
import org.apache.james.smtpserver.CommandHandler;
import org.apache.james.smtpserver.SMTPSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class CheckRepositoriesBlockingRcptCmdHandler implements CommandHandler, Configurable {
    private final static Logger logger = LoggerFactory.getLogger(CheckRepositoriesBlockingRcptCmdHandler.class);

    /*
     * The repository URLs that will be monitored to check if they do not grow too big
     */
    private List<String> repositories;

    /*
     * If a the number of items in the monitored repositories exceed this limit the message is rejected
     */
    private int repositoryUpperLimit = 1000;

    /*
     * If mail was blocked because the number of items in a repository exceeded repositoryUpperLimit and the number of 
     * items becomes below repositoryLowerLimit receiving is restored. 
     * 
     */
    private int repositoryLowerLimit = 500;

    /*
     * The number of milliseconds between checks for queue full
     */
    private long checkInterval = 60000;

    /*
     * The SMTP status to return when one of the repositories is exceeds the upper limit
     */
    private String rejectCode = "452";

    /*
     * Used to track the last time a check was done
     */
    private AtomicLong lastCheck = new AtomicLong();

    /*
     * True if one of the monitored repositories is over the limit
     */
    private AtomicBoolean overLimit = new AtomicBoolean();

    @Override
    public void configure(Configuration handlerConfiguration) throws ConfigurationException {
        logger.info("Configuring CommandHandler");

        Configuration[] repositoryConfigs = handlerConfiguration.getChild("repositories").getChildren("repository");

        repositories = Collections.synchronizedList(new ArrayList<String>(repositoryConfigs.length));

        for (Configuration repositoryConfig : repositoryConfigs) {
            repositories.add(repositoryConfig.getValue());
        }

        Configuration config = handlerConfiguration.getChild("rejectCode", false);

        if (config != null) {
            rejectCode = config.getValue("452");
        }

        config = handlerConfiguration.getChild("repositoryUpperLimit", false);

        if (config != null) {
            repositoryUpperLimit = config.getValueAsInteger(1000);
        }

        config = handlerConfiguration.getChild("repositoryLowerLimit", false);

        if (config != null) {
            repositoryLowerLimit = config.getValueAsInteger(500);
        }

        config = handlerConfiguration.getChild("checkInterval", false);

        if (config != null) {
            checkInterval = config.getValueAsLong(60000);
        }

        StrBuilder sb = new StrBuilder();

        sb.append("Repositories: ");
        sb.appendWithSeparators(repositories, ", ");
        sb.appendSeparator("; ");
        sb.append("rejectCode: ");
        sb.append(rejectCode);
        sb.appendSeparator("; ");
        sb.append("repositoryUpperLimit: ");
        sb.append(repositoryUpperLimit);
        sb.appendSeparator("; ");
        sb.append("repositoryLowerLimit: ");
        sb.append(repositoryLowerLimit);
        sb.appendSeparator("; ");
        sb.append("checkInterval: ");
        sb.append(checkInterval);

        logger.info(sb.toString());
    }

    @Override
    public void onCommand(SMTPSession session) {
        try {
            checkRepositories();
        } catch (RepositoryOverLimitException e) {
            logger.warn(e.getMessage());

            String response = rejectCode + " " + e.getMessage();

            session.writeResponse(response);
        }
    }

    private void checkRepositories() throws RepositoryOverLimitException {
        long now = System.currentTimeMillis();

        if ((now - lastCheck.longValue()) >= checkInterval) {
            lastCheck.set(now);

            ServiceManager serviceManager = SystemServices.getAvalonServiceManager();

            for (String repositoryURL : repositories) {
                MailRepository mailRepository;

                try {
                    mailRepository = new JamesStoreManager(serviceManager).getMailRepository(repositoryURL);
                } catch (ServiceException e) {
                    logger.error("Error getting mailRepository for URL: " + repositoryURL);

                    continue;
                }

                Iterator<?> keyIterator;

                try {
                    keyIterator = mailRepository.list();
                } catch (MessagingException e) {
                    logger.error("Error getting list for URL: " + repositoryURL);

                    continue;
                }

                int size = 0;

                while (keyIterator.hasNext()) {
                    keyIterator.next();

                    size++;
                }

                logger.debug("size of repository " + repositoryURL + " is " + size);

                if (size > repositoryUpperLimit) {
                    overLimit.set(true);

                    throw new RepositoryOverLimitException(
                            repositoryURL + " repository is over the upperLimit of " + repositoryUpperLimit);
                }

                if (overLimit.get() && size > repositoryLowerLimit) {
                    /*
                     * The mail is blocked because there was an overlimit on one of the queue's and the size of the queue is
                     * is now less than the lower limit. It can happen that one queue was over the upper limit but that that
                     * same queue is now less than the lower limit but another queue is not. We will still block it until
                     * all queues are below the lower limit. If we want to track each individual queue we need to keep
                     * these stats for each queue.
                     */
                    throw new RepositoryOverLimitException(
                            repositoryURL + " repository is over the lowerLimit of " + repositoryLowerLimit);
                }
            }
        } else {
            if (overLimit.get()) {
                /*
                 * We did not currently check the queue's but the previous check reported a over limit
                 */
                throw new RepositoryOverLimitException(
                        "The cached limit is still over the upperLimit of " + repositoryUpperLimit);
            }
        }

        if (overLimit.get()) {
            logger.info("Mail is accepted again because all repository queue's are below the lower level.");
        }

        overLimit.set(false);
    }
}