/************************************************************************
    * Copyright (c) 2000-2006 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.transport.mailets;
  
  import org.apache.avalon.cornerstone.services.store.Store;
  import org.apache.avalon.framework.configuration.DefaultConfiguration;
  import org.apache.avalon.framework.container.ContainerUtil;
  import org.apache.avalon.framework.service.ServiceException;
  import org.apache.avalon.framework.service.ServiceManager;
  import org.apache.james.Constants;
  import org.apache.james.services.SpoolRepository;
  import org.apache.mailet.GenericMailet;
  import org.apache.mailet.HostAddress;
  import org.apache.mailet.Mail;
  import org.apache.mailet.MailAddress;
  import org.apache.mailet.MailetContext;
  import org.apache.oro.text.regex.MalformedPatternException;
  import org.apache.oro.text.regex.MatchResult;
  import org.apache.oro.text.regex.Pattern;
  import org.apache.oro.text.regex.Perl5Compiler;
  import org.apache.oro.text.regex.Perl5Matcher;
  
  import com.sun.mail.smtp.SMTPAddressFailedException;
  import com.sun.mail.smtp.SMTPAddressSucceededException;
  import com.sun.mail.smtp.SMTPSendFailedException;
  import com.sun.mail.smtp.SMTPTransport;
  
  import javax.mail.Address;
  import javax.mail.MessagingException;
  import javax.mail.SendFailedException;
  import javax.mail.Session;
  import javax.mail.Transport;
  import javax.mail.internet.InternetAddress;
  import javax.mail.internet.MimeMessage;
  import javax.mail.internet.MimeMultipart;
  import javax.mail.internet.MimePart;
  import javax.mail.internet.ParseException;
  
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.StringWriter;
  import java.net.ConnectException;
  import java.net.InetAddress;
  import java.net.SocketException;
  import java.net.UnknownHostException;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Hashtable;
  import java.util.Iterator;
  import java.util.Locale;
  import java.util.Properties;
  import java.util.StringTokenizer;
  import java.util.Vector;
  
  
  /***
   * Receives a MessageContainer from JamesSpoolManager and takes care of delivery
   * the message to remote hosts. If for some reason mail can't be delivered
   * store it in the "outgoing" Repository and set an Alarm. After the next "delayTime" the
   * Alarm will wake the servlet that will try to send it again. After "maxRetries"
   * the mail will be considered undeliverable and will be returned to sender.
   *
   * TO DO (in priority):
   * 1. Support a gateway (a single server where all mail will be delivered) (DONE)
   * 2. Provide better failure messages (DONE)
   * 3. More efficiently handle numerous recipients
   * 4. Migrate to use Phoenix for the delivery threads
   *
   * You really want to read the JavaMail documentation if you are
   * working in here, and you will want to view the list of JavaMail
   * attributes, which are documented here:
   *
   * http://java.sun.com/products/javamail/1.3/docs/javadocs/com/sun/mail/smtp/package-summary.html
   *
   * as well as other places.
   *
   * @version CVS $Revision: 450877 $ $Date: 2006-09-28 14:49:38 +0000 (gio, 28 set 2006) $
   */
  public class RemoteDelivery extends GenericMailet implements Runnable {
  
      private static final long DEFAULT_DELAY_TIME = 21600000; // default is 6*60*60*1000 millis (6 hours)
     private static final String PATTERN_STRING =
         "//s*([0-9]*//s*[//*])?//s*([0-9]+)//s*([a-z,A-Z]*)//s*";//pattern to match
                                                                  //[attempts*]delay[units]
                                             
     private static Pattern PATTERN = null; //the compiled pattern of the above String
     private static final HashMap MULTIPLIERS = new HashMap (10); //holds allowed units for delaytime together with
                                                                 //the factor to turn it into the equivalent time in msec
 
     /*
      * Static initializer.<p>
      * Compiles pattern for processing delaytime entries.<p>
      * Initializes MULTIPLIERS with the supported unit quantifiers
      */
     static {
         try {
             Perl5Compiler compiler = new Perl5Compiler(); 
             PATTERN = compiler.compile(PATTERN_STRING, Perl5Compiler.READ_ONLY_MASK);
         } catch(MalformedPatternException mpe) {
             //this should not happen as the pattern string is hardcoded.
             System.err.println ("Malformed pattern: " + PATTERN_STRING);
             mpe.printStackTrace (System.err);
         }
         //add allowed units and their respective multiplier
         MULTIPLIERS.put ("msec", new Integer (1));
         MULTIPLIERS.put ("msecs", new Integer (1));
         MULTIPLIERS.put ("sec",  new Integer (1000));
         MULTIPLIERS.put ("secs",  new Integer (1000));
         MULTIPLIERS.put ("minute", new Integer (1000*60));
         MULTIPLIERS.put ("minutes", new Integer (1000*60));
         MULTIPLIERS.put ("hour", new Integer (1000*60*60));
         MULTIPLIERS.put ("hours", new Integer (1000*60*60));
         MULTIPLIERS.put ("day", new Integer (1000*60*60*24));
         MULTIPLIERS.put ("days", new Integer (1000*60*60*24));
     }
     
     /***
      * This filter is used in the accept call to the spool.
      * It will select the next mail ready for processing according to the mails
      * retrycount and lastUpdated time
      **/
     private class MultipleDelayFilter implements SpoolRepository.AcceptFilter
     {
         /***
          * holds the time to wait for the youngest mail to get ready for processing
          **/
         long youngest = 0;
 
         /***
          * Uses the getNextDelay to determine if a mail is ready for processing based on the delivered parameters
          * errorMessage (which holds the retrycount), lastUpdated and state
          * @param key the name/key of the message
          * @param state the mails state
          * @param lastUpdated the mail was last written to the spool at this time.
          * @param errorMessage actually holds the retrycount as a string (see failMessage below)
          **/
         public boolean accept (String key, String state, long lastUpdated, String errorMessage) {
             if (state.equals(Mail.ERROR)) {
                 //Test the time...
                 int retries = Integer.parseInt(errorMessage);
                 
                 // If the retries count is 0 we should try to send the mail now!
                 if (retries == 0) return true;
                 
                 long delay = getNextDelay (retries);
                 long timeToProcess = delay + lastUpdated;
 
                 
                 if (System.currentTimeMillis() > timeToProcess) {
                     //We're ready to process this again
                     return true;
                 } else {
                     //We're not ready to process this.
                     if (youngest == 0 || youngest > timeToProcess) {
                         //Mark this as the next most likely possible mail to process
                         youngest = timeToProcess;
                     }
                     return false;
                 }
             } else {
                 //This mail is good to go... return the key
                 return true;
             }
         }
 
         /***
          * @return the optimal time the SpoolRepository.accept(AcceptFilter) method should wait before
          * trying to find a mail ready for processing again.
          **/
         public long getWaitTime () {
             if (youngest == 0) {
                 return 0;
             } else {
                 long duration = youngest - System.currentTimeMillis();
                 youngest = 0; //get ready for next run
                 return duration <= 0 ? 1 : duration;
             }
         }
     }
 
     /***
      * Controls certain log messages
      */
     private boolean isDebug = false;
 
     private SpoolRepository outgoing; // The spool of outgoing mail
     private long[] delayTimes; //holds expanded delayTimes
     private int maxRetries = 5; // default number of retries
     private long smtpTimeout = 180000;  //default number of ms to timeout on smtp delivery
     private boolean sendPartial = false; // If false then ANY address errors will cause the transmission to fail
     private int connectionTimeout = 60000;  // The amount of time JavaMail will wait before giving up on a socket connect()
     private int deliveryThreadCount = 1; // default number of delivery threads
     private Collection gatewayServer = null; // the server(s) to send all email to
     private String authUser = null; // auth for gateway server
     private String authPass = null; // password for gateway server
     private String bindAddress = null; // JavaMail delivery socket binds to this local address. If null the JavaMail default will be used.
     private boolean isBindUsed = false; // true, if the bind configuration
                                         // parameter is supplied, RemoteDeliverySocketFactory
                                         // will be used in this case
     private Collection deliveryThreads = new Vector();
     private volatile boolean destroyed = false; //Flag that the run method will check and end itself if set to true
     private String bounceProcessor = null; // the processor for creating Bounces
 
     private Perl5Matcher delayTimeMatcher; //matcher use at init time to parse delaytime parameters
     private MultipleDelayFilter delayFilter = new MultipleDelayFilter ();//used by accept to selcet the next mail ready for processing
 
     
     /***
      * Initialize the mailet
      */
     public void init() throws MessagingException {
         isDebug = (getInitParameter("debug") == null) ? false : new Boolean(getInitParameter("debug")).booleanValue();
         ArrayList delay_times_list = new ArrayList();
         try {
             if (getInitParameter("delayTime") != null) {
                 delayTimeMatcher = new Perl5Matcher();
                 String delay_times = getInitParameter("delayTime");
                 //split on comma's
                 StringTokenizer st = new StringTokenizer (delay_times,",");
                 while (st.hasMoreTokens()) {
                     String delay_time = st.nextToken();
                     delay_times_list.add (new Delay(delay_time));
                 }
             } else {
                 //use default delayTime.
                 delay_times_list.add (new Delay());
             }
         } catch (Exception e) {
             log("Invalid delayTime setting: " + getInitParameter("delayTime"));
         }
         try {
             if (getInitParameter("maxRetries") != null) {
                 maxRetries = Integer.parseInt(getInitParameter("maxRetries"));
             }
             //check consistency with delay_times_list attempts
             int total_attempts = calcTotalAttempts (delay_times_list);
             if (total_attempts > maxRetries) {
                 log("Total number of delayTime attempts exceeds maxRetries specified. Increasing maxRetries from "+maxRetries+" to "+total_attempts);
                 maxRetries = total_attempts;
             } else {
                 int extra = maxRetries - total_attempts;
                 if (extra != 0) {
                     log("maxRetries is larger than total number of attempts specified. Increasing last delayTime with "+extra+" attempts ");
 
                     if (delay_times_list.size() != 0) { 
                         Delay delay = (Delay)delay_times_list.get (delay_times_list.size()-1); //last Delay
                         delay.setAttempts (delay.getAttempts()+extra);
                         log("Delay of "+delay.getDelayTime()+" msecs is now attempted: "+delay.getAttempts()+" times");
                     } else {
                         log ("NO, delaytimes cannot continue");
                     }
                 }
             }
             delayTimes = expandDelays (delay_times_list);
             
         } catch (Exception e) {
             log("Invalid maxRetries setting: " + getInitParameter("maxRetries"));
         }
         try {
             if (getInitParameter("timeout") != null) {
                 smtpTimeout = Integer.parseInt(getInitParameter("timeout"));
             }
         } catch (Exception e) {
             log("Invalid timeout setting: " + getInitParameter("timeout"));
         }
 
         try {
             if (getInitParameter("connectiontimeout") != null) {
                 connectionTimeout = Integer.parseInt(getInitParameter("connectiontimeout"));
             }
         } catch (Exception e) {
             log("Invalid timeout setting: " + getInitParameter("timeout"));
         }
         sendPartial = (getInitParameter("sendpartial") == null) ? false : new Boolean(getInitParameter("sendpartial")).booleanValue();
 
         bounceProcessor = getInitParameter("bounceProcessor");
 
         String gateway = getInitParameter("gateway");
         String gatewayPort = getInitParameter("gatewayPort");
 
         if (gateway != null) {
             gatewayServer = new ArrayList();
             StringTokenizer st = new StringTokenizer(gateway, ",") ;
             while (st.hasMoreTokens()) {
                 String server = st.nextToken().trim() ;
                 if (server.indexOf(':') < 0 && gatewayPort != null) {
                     server += ":";
                     server += gatewayPort;
                 }
 
                 if (isDebug) log("Adding SMTP gateway: " + server) ;
                 gatewayServer.add(server);
             }
             authUser = getInitParameter("gatewayusername");
             authPass = getInitParameter("gatewayPassword");
         }
 
         ServiceManager compMgr = (ServiceManager)getMailetContext().getAttribute(Constants.AVALON_COMPONENT_MANAGER);
         String outgoingPath = getInitParameter("outgoing");
         if (outgoingPath == null) {
             outgoingPath = "file:///../var/mail/outgoing";
         }
 
         try {
             // Instantiate the a MailRepository for outgoing mails
             Store mailstore = (Store) compMgr.lookup(Store.ROLE);
 
             DefaultConfiguration spoolConf
                 = new DefaultConfiguration("repository", "generated:RemoteDelivery.java");
             spoolConf.setAttribute("destinationURL", outgoingPath);
             spoolConf.setAttribute("type", "SPOOL");
             outgoing = (SpoolRepository) mailstore.select(spoolConf);
         } catch (ServiceException cnfe) {
             log("Failed to retrieve Store component:" + cnfe.getMessage());
         } catch (Exception e) {
             log("Failed to retrieve Store component:" + e.getMessage());
         }
 
         //Start up a number of threads
         try {
             deliveryThreadCount = Integer.parseInt(getInitParameter("deliveryThreads"));
         } catch (Exception e) {
         }
         for (int i = 0; i < deliveryThreadCount; i++) {
             StringBuffer nameBuffer =
                 new StringBuffer(32)
                         .append("Remote delivery thread (")
                         .append(i)
                         .append(")");
             Thread t = new Thread(this, nameBuffer.toString());
             t.start();
             deliveryThreads.add(t);
         }
 
         bindAddress = getInitParameter("bind");
         isBindUsed = bindAddress != null;
         try {
             if (isBindUsed) RemoteDeliverySocketFactory.setBindAdress(bindAddress);
         } catch (UnknownHostException e) {
             log("Invalid bind setting (" + bindAddress + "): " + e.toString());
         }
     }
 
     /*
      * private method to log the extended SendFailedException introduced in JavaMail 1.3.2.
      */
     private void logSendFailedException(SendFailedException sfe) {
         if (isDebug) {
             MessagingException me = sfe;
             if (me instanceof SMTPSendFailedException) {
                 SMTPSendFailedException ssfe = (SMTPSendFailedException)me;
                 log("SMTP SEND FAILED:");
                 log(ssfe.toString());
                 log("  Command: " + ssfe.getCommand());
                 log("  RetCode: " + ssfe.getReturnCode());
                 log("  Response: " + ssfe.getMessage());
             } else {
                 log("Send failed: " + me.toString());
             }
             Exception ne;
             while ((ne = me.getNextException()) != null && ne instanceof MessagingException) {
                 me = (MessagingException)ne;
                 if (me instanceof SMTPAddressFailedException) {
                     SMTPAddressFailedException e = (SMTPAddressFailedException)me;
                     log("ADDRESS FAILED:");
                     log(e.toString());
                     log("  Address: " + e.getAddress());
                     log("  Command: " + e.getCommand());
                     log("  RetCode: " + e.getReturnCode());
                     log("  Response: " + e.getMessage());
                 } else if (me instanceof SMTPAddressSucceededException) {
                     log("ADDRESS SUCCEEDED:");
                     SMTPAddressSucceededException e = (SMTPAddressSucceededException)me;
                     log(e.toString());
                     log("  Address: " + e.getAddress());
                     log("  Command: " + e.getCommand());
                     log("  RetCode: " + e.getReturnCode());
                     log("  Response: " + e.getMessage());
                 }
             }
         }
     }
 
     /***
      * We can assume that the recipients of this message are all going to the same
      * mail server.  We will now rely on the DNS server to do DNS MX record lookup
      * and try to deliver to the multiple mail servers.  If it fails, it should
      * throw an exception.
      *
      * Creation date: (2/24/00 11:25:00 PM)
      * @param mail org.apache.james.core.MailImpl
      * @param session javax.mail.Session
      * @return boolean Whether the delivery was successful and the message can be deleted
      */
     private boolean deliver(Mail mail, Session session) {
         try {
             if (isDebug) {
                 log("Attempting to deliver " + mail.getName());
             }
             MimeMessage message = mail.getMessage();
 
             //Create an array of the recipients as InternetAddress objects
             Collection recipients = mail.getRecipients();
             InternetAddress addr[] = new InternetAddress[recipients.size()];
             int j = 0;
             for (Iterator i = recipients.iterator(); i.hasNext(); j++) {
                 MailAddress rcpt = (MailAddress)i.next();
                 addr[j] = rcpt.toInternetAddress();
             }
 
             if (addr.length <= 0) {
                 log("No recipients specified... not sure how this could have happened.");
                 return true;
             }
 
             //Figure out which servers to try to send to.  This collection
             //  will hold all the possible target servers
             Iterator targetServers = null;
             if (gatewayServer == null) {
                 MailAddress rcpt = (MailAddress) recipients.iterator().next();
                 String host = rcpt.getHost();
 
                 //Lookup the possible targets
                 targetServers = getMailetContext().getSMTPHostAddresses(host);
                 if (!targetServers.hasNext()) {
                     log("No mail server found for: " + host);
                     StringBuffer exceptionBuffer =
                         new StringBuffer(128)
                         .append("There are no DNS entries for the hostname ")
                         .append(host)
                         .append(".  I cannot determine where to send this message.");
                     return failMessage(mail, new MessagingException(exceptionBuffer.toString()), false);
                 }
             } else {
                 targetServers = getGatewaySMTPHostAddresses(gatewayServer);
             }
 
             MessagingException lastError = null;
 
             while ( targetServers.hasNext()) {
                 try {
                     HostAddress outgoingMailServer = (HostAddress) targetServers.next();
                     StringBuffer logMessageBuffer =
                         new StringBuffer(256)
                         .append("Attempting delivery of ")
                         .append(mail.getName())
                         .append(" to host ")
                         .append(outgoingMailServer.getHostName())
                         .append(" at ")
                         .append(outgoingMailServer.getHost())
                         .append(" for addresses ")
                         .append(Arrays.asList(addr));
                     log(logMessageBuffer.toString());
 
                     Properties props = session.getProperties();
                     if (mail.getSender() == null) {
                         props.put("mail.smtp.from", "<>");
                     } else {
                         String sender = mail.getSender().toString();
                         props.put("mail.smtp.from", sender);
                     }
 
                     //Many of these properties are only in later JavaMail versions
                     //"mail.smtp.ehlo"  //default true
                     //"mail.smtp.auth"  //default false
                     //"mail.smtp.dsn.ret"  //default to nothing... appended as RET= after MAIL FROM line.
                     //"mail.smtp.dsn.notify" //default to nothing...appended as NOTIFY= after RCPT TO line.
 
                     Transport transport = null;
                     try {
                         transport = session.getTransport(outgoingMailServer);
                         try {
                             if (authUser != null) {
                                 transport.connect(outgoingMailServer.getHostName(), authUser, authPass);
                             } else {
                                 transport.connect();
                             }
                         } catch (MessagingException me) {
                             // Any error on connect should cause the mailet to attempt
                             // to connect to the next SMTP server associated with this
                             // MX record.  Just log the exception.  We'll worry about
                             // failing the message at the end of the loop.
                             log(me.getMessage());
                             continue;
                         }
                         // if the transport is a SMTPTransport (from sun) some
                         // performance enhancement can be done.
                         if (transport instanceof SMTPTransport)  {
                             SMTPTransport smtpTransport = (SMTPTransport) transport;
                            
                             // if the message is alredy 8bit or binary and the
                             // server doesn't support the 8bit extension it has
                             // to be converted to 7bit. Javamail api doesn't perform
                             // that conversion, but it is required to be a
                             // rfc-compliant smtp server.
                             
                             // Temporarily disabled. See JAMES-638
                             /*
                             if (!smtpTransport.supportsExtension("8BITMIME")) { 
                                 try {
                                     convertTo7Bit(message);
                                 } catch (IOException e) {
                                     // An error has occured during the 7bit conversion.
                                     // The error is logged and the message is sent anyway.
                                     
                                     log("Error during the conversion to 7 bit.", e);
                                 }
                             }
                             */
                             
                             /*
                              * Workaround for a javamail 1.3.2 bug: if
                              * a message is sent without encoding information
                              * and the 8bit allow property is set an exception
                              * is trown during the mail delivery.
                              */
                             
                             try {
                                 setEncodingIfMissing(message);
                             } catch (IOException e) {
                                 log("Error while adding encoding information to the message", e);
                             }
                         } else {
                             // If the transport is not the one
                             // developed by Sun we are not sure of how it
                             // handles the 8 bit mime stuff,
                             // so I convert the message to 7bit.
                             try {
                                 convertTo7Bit(message);
                             } catch (IOException e) {
                                 log("Error during the conversion to 7 bit.", e);
                             }
                         }
                         transport.sendMessage(message, addr);
                     } finally {
                         if (transport != null) {
                             transport.close();
                             transport = null;
                         }
                     }
                     logMessageBuffer =
                                       new StringBuffer(256)
                                       .append("Mail (")
                                       .append(mail.getName())
                                       .append(") sent successfully to ")
                                       .append(outgoingMailServer.getHostName())
                                       .append(" at ")
                                       .append(outgoingMailServer.getHost())
                                       .append(" for ")
                                       .append(mail.getRecipients());
                     log(logMessageBuffer.toString());
                     return true;
                 } catch (SendFailedException sfe) {
                     logSendFailedException(sfe);
 
                     if (sfe.getValidSentAddresses() != null) {
                         Address[] validSent = sfe.getValidSentAddresses();
                         if (validSent.length > 0) {
                             StringBuffer logMessageBuffer =
                                 new StringBuffer(256)
                                 .append("Mail (")
                                 .append(mail.getName())
                                 .append(") sent successfully for ")
                                 .append(Arrays.asList(validSent));
                             log(logMessageBuffer.toString());
                         }
                     }
 
                     /* SMTPSendFailedException introduced in JavaMail 1.3.2, and provides detailed protocol reply code for the operation */
                     if (sfe instanceof SMTPSendFailedException) {
                         SMTPSendFailedException ssfe = (SMTPSendFailedException) sfe;
                         // if 5xx, terminate this delivery attempt by re-throwing the exception.
                         if (ssfe.getReturnCode() >= 500 && ssfe.getReturnCode() <= 599) throw sfe;
                     }
 
                     if (sfe.getValidUnsentAddresses() != null
                         && sfe.getValidUnsentAddresses().length > 0) {
                         if (isDebug) log("Send failed, " + sfe.getValidUnsentAddresses().length + " valid addresses remain, continuing with any other servers");
                         lastError = sfe;
                         continue;
                     } else {
                         // There are no valid addresses left to send, so rethrow
                         throw sfe;
                     }
                 } catch (MessagingException me) {
                     //MessagingException are horribly difficult to figure out what actually happened.
                     StringBuffer exceptionBuffer =
                         new StringBuffer(256)
                         .append("Exception delivering message (")
                         .append(mail.getName())
                         .append(") - ")
                         .append(me.getMessage());
                     log(exceptionBuffer.toString());
                     if ((me.getNextException() != null) &&
                           (me.getNextException() instanceof java.io.IOException)) {
                         //This is more than likely a temporary failure
 
                         // If it's an IO exception with no nested exception, it's probably
                         // some socket or weird I/O related problem.
                         lastError = me;
                         continue;
                     }
                     // This was not a connection or I/O error particular to one
                     // SMTP server of an MX set.  Instead, it is almost certainly
                     // a protocol level error.  In this case we assume that this
                     // is an error we'd encounter with any of the SMTP servers
                     // associated with this MX record, and we pass the exception
                     // to the code in the outer block that determines its severity.
                     throw me;
                 }
             } // end while
             //If we encountered an exception while looping through,
             //throw the last MessagingException we caught.  We only
             //do this if we were unable to send the message to any
             //server.  If sending eventually succeeded, we exit
             //deliver() though the return at the end of the try
             //block.
             if (lastError != null) {
                 throw lastError;
             }
         } catch (SendFailedException sfe) {
         logSendFailedException(sfe);
 
             Collection recipients = mail.getRecipients();
 
             boolean deleteMessage = false;
 
             /*
              * If you send a message that has multiple invalid
              * addresses, you'll get a top-level SendFailedException
              * that that has the valid, valid-unsent, and invalid
              * address lists, with all of the server response messages
              * will be contained within the nested exceptions.  [Note:
              * the content of the nested exceptions is implementation
              * dependent.]
              *
              * sfe.getInvalidAddresses() should be considered permanent.
              * sfe.getValidUnsentAddresses() should be considered temporary.
              *
              * JavaMail v1.3 properly populates those collections based
              * upon the 4xx and 5xx response codes to RCPT TO.  Some
              * servers, such as Yahoo! don't respond to the RCPT TO,
              * and provide a 5xx reply after DATA.  In that case, we
              * will pick up the failure from SMTPSendFailedException.
              *
              */
 
             /* SMTPSendFailedException introduced in JavaMail 1.3.2, and provides detailed protocol reply code for the operation */
             if (sfe instanceof SMTPSendFailedException) {
                 // If we got an SMTPSendFailedException, use its RetCode to determine default permanent/temporary failure
                 SMTPSendFailedException ssfe = (SMTPSendFailedException) sfe;
                 deleteMessage = (ssfe.getReturnCode() >= 500 && ssfe.getReturnCode() <= 599);
             } else {
                 // Sometimes we'll get a normal SendFailedException with nested SMTPAddressFailedException, so use the latter RetCode
                 MessagingException me = sfe;
                 Exception ne;
                 while ((ne = me.getNextException()) != null && ne instanceof MessagingException) {
                     me = (MessagingException)ne;
                     if (me instanceof SMTPAddressFailedException) {
                         SMTPAddressFailedException ssfe = (SMTPAddressFailedException)me;
                         deleteMessage = (ssfe.getReturnCode() >= 500 && ssfe.getReturnCode() <= 599);
                     }
                 }
             }
 
             // log the original set of intended recipients
             if (isDebug) log("Recipients: " + recipients);
 
             if (sfe.getInvalidAddresses() != null) {
                 Address[] address = sfe.getInvalidAddresses();
                 if (address.length > 0) {
                     recipients.clear();
                     for (int i = 0; i < address.length; i++) {
                         try {
                             recipients.add(new MailAddress(address[i].toString()));
                         } catch (ParseException pe) {
                             // this should never happen ... we should have
                             // caught malformed addresses long before we
                             // got to this code.
                             log("Can't parse invalid address: " + pe.getMessage());
                         }
                     }
                     if (isDebug) log("Invalid recipients: " + recipients);
                     deleteMessage = failMessage(mail, sfe, true);
                 }
             }
 
             if (sfe.getValidUnsentAddresses() != null) {
                 Address[] address = sfe.getValidUnsentAddresses();
                 if (address.length > 0) {
                     recipients.clear();
                     for (int i = 0; i < address.length; i++) {
                         try {
                             recipients.add(new MailAddress(address[i].toString()));
                         } catch (ParseException pe) {
                             // this should never happen ... we should have
                             // caught malformed addresses long before we
                             // got to this code.
                             log("Can't parse unsent address: " + pe.getMessage());
                         }
                     }
                     if (isDebug) log("Unsent recipients: " + recipients);
                     if (sfe instanceof SMTPSendFailedException) {
                         SMTPSendFailedException ssfe = (SMTPSendFailedException) sfe;
                         deleteMessage = failMessage(mail, sfe, ssfe.getReturnCode() >= 500 && ssfe.getReturnCode() <= 599);
                     } else {
                         deleteMessage = failMessage(mail, sfe, false);
                     }
                 }
             }
 
             return deleteMessage;
         } catch (MessagingException ex) {
             // We should do a better job checking this... if the failure is a general
             // connect exception, this is less descriptive than more specific SMTP command
             // failure... have to lookup and see what are the various Exception
             // possibilities
 
             // Unable to deliver message after numerous tries... fail accordingly
 
             // We check whether this is a 5xx error message, which
             // indicates a permanent failure (like account doesn't exist
             // or mailbox is full or domain is setup wrong).
             // We fail permanently if this was a 5xx error
             return failMessage(mail, ex, ('5' == ex.getMessage().charAt(0)));
         }
 
         /* If we get here, we've exhausted the loop of servers without
          * sending the message or throwing an exception.  One case
          * where this might happen is if we get a MessagingException on
          * each transport.connect(), e.g., if there is only one server
          * and we get a connect exception.
          */
         return failMessage(mail, new MessagingException("No mail server(s) available at this time."), false);
     }
 
     /***
      * Converts a message to 7 bit.
      * 
      * @param message
      * @return
      */
     private void convertTo7Bit(MimePart part) throws MessagingException, IOException {
         if (part.isMimeType("multipart/*")) {
             MimeMultipart parts = (MimeMultipart) part.getContent();
             int count = parts.getCount();
             for (int i = 0; i < count; i++) {
                 convertTo7Bit((MimePart)parts.getBodyPart(i));
             }
         } else {
             if (part.isMimeType("text/*")) {
                 part.setHeader("Content-Transfer-Encoding", "quoted-printable");
                 part.addHeader("X-MIME-Autoconverted", "from 8bit to quoted-printable by "+getMailetContext().getServerInfo());
             } else {
                 // if the part doesn't contain text it will be base64 encoded.
                 part.setHeader("Content-Transfer-Encoding", "base64");
                 part.addHeader("X-MIME-Autoconverted", "from 8bit to base64 by "+getMailetContext().getServerInfo());
             }
         }
     }
     
     /***
      * Adds an encoding information to each text mime part. This is a workaround
      * for a javamail 1.3.2 bug: if a message is sent without encoding
      * information a null pointer exception is thrown during the message
      * delivery.
      * 
      * @param part
      * @throws MessagingException
      * @throws IOException
      */
     private void setEncodingIfMissing(MimePart part) throws MessagingException, IOException {
         if (part.isMimeType("text/*")) {
             String enc = part.getEncoding();
             if (enc == null) part.setHeader("Content-Transfer-Encoding", "7bit");
         } else if (part.isMimeType("multipart/*")) {
             Object content = part.getContent();
             if (content instanceof MimeMultipart) {
                 MimeMultipart parts = (MimeMultipart) content;
                 int count = parts.getCount();
                 for (int i = 0; i < count; i++) {
                     setEncodingIfMissing((MimePart)parts.getBodyPart(i));
                 }
             }
         }
     }
     
     /***
      * Insert the method's description here.
      * Creation date: (2/25/00 1:14:18 AM)
      * @param mail org.apache.james.core.MailImpl
      * @param exception javax.mail.MessagingException
      * @param boolean permanent
      * @return boolean Whether the message failed fully and can be deleted
      */
     private boolean failMessage(Mail mail, MessagingException ex, boolean permanent) {
         StringWriter sout = new StringWriter();
         PrintWriter out = new PrintWriter(sout, true);
         if (permanent) {
             out.print("Permanent");
         } else {
             out.print("Temporary");
         }
         StringBuffer logBuffer =
             new StringBuffer(64)
                 .append(" exception delivering mail (")
                 .append(mail.getName())
                 .append(": ");
         out.print(logBuffer.toString());
         if (isDebug) ex.printStackTrace(out);
         log(sout.toString());
         if (!permanent) {
             if (!mail.getState().equals(Mail.ERROR)) {
                 mail.setState(Mail.ERROR);
                 mail.setErrorMessage("0");
                 mail.setLastUpdated(new Date());
             }
             int retries = Integer.parseInt(mail.getErrorMessage());
             if (retries < maxRetries) {
                 logBuffer =
                     new StringBuffer(128)
                             .append("Storing message ")
                             .append(mail.getName())
                             .append(" into outgoing after ")
                             .append(retries)
                             .append(" retries");
                 log(logBuffer.toString());
                 ++retries;
                 mail.setErrorMessage(retries + "");
                 mail.setLastUpdated(new Date());
                 return false;
             } else {
                 logBuffer =
                     new StringBuffer(128)
                             .append("Bouncing message ")
                             .append(mail.getName())
                             .append(" after ")
                             .append(retries)
                             .append(" retries");
                 log(logBuffer.toString());
             }
         }
 
         if (mail.getSender() == null) {
             log("Null Sender: no bounce will be generated for " + mail.getName());
             return true;
         }
 
         if (bounceProcessor != null) {
             // do the new DSN bounce
             // setting attributes for DSN mailet
             mail.setAttribute("delivery-error", ex);
             mail.setState(bounceProcessor);
             // re-insert the mail into the spool for getting it passed to the dsn-processor
             MailetContext mc = getMailetContext();
             try {
                 mc.sendMail(mail);
             } catch (MessagingException e) {
                 // we shouldn't get an exception, because the mail was already processed
                 log("Exception re-inserting failed mail: ", e);
             }
         } else {
             // do an old style bounce
             bounce(mail, ex);
         }
         return true;
     }
 
     private void bounce(Mail mail, MessagingException ex) {
         StringWriter sout = new StringWriter();
         PrintWriter out = new PrintWriter(sout, true);
         String machine = "[unknown]";
         try {
             InetAddress me = InetAddress.getLocalHost();
             machine = me.getHostName();
         } catch(Exception e){
             machine = "[address unknown]";
         }
         StringBuffer bounceBuffer =
             new StringBuffer(128)
                     .append("Hi. This is the James mail server at ")
                     .append(machine)
                     .append(".");
         out.println(bounceBuffer.toString());
         out.println("I'm afraid I wasn't able to deliver your message to the following addresses.");
         out.println("This is a permanent error; I've given up. Sorry it didn't work out.  Below");
         out.println("I include the list of recipients and the reason why I was unable to deliver");
         out.println("your message.");
         out.println();
         for (Iterator i = mail.getRecipients().iterator(); i.hasNext(); ) {
             out.println(i.next());
         }
         if (ex.getNextException() == null) {
             out.println(ex.getMessage().trim());
         } else {
             Exception ex1 = ex.getNextException();
             if (ex1 instanceof SendFailedException) {
                 out.println("Remote mail server told me: " + ex1.getMessage().trim());
             } else if (ex1 instanceof UnknownHostException) {
                 out.println("Unknown host: " + ex1.getMessage().trim());
                 out.println("This could be a DNS server error, a typo, or a problem with the recipient's mail server.");
             } else if (ex1 instanceof ConnectException) {
                 //Already formatted as "Connection timed out: connect"
                 out.println(ex1.getMessage().trim());
             } else if (ex1 instanceof SocketException) {
                 out.println("Socket exception: " + ex1.getMessage().trim());
             } else {
                 out.println(ex1.getMessage().trim());
             }
         }
         out.println();
 
         log("Sending failure message " + mail.getName());
         try {
             getMailetContext().bounce(mail, sout.toString());
         } catch (MessagingException me) {
             log("Encountered unexpected messaging exception while bouncing message: " + me.getMessage());
         } catch (Exception e) {
             log("Encountered unexpected exception while bouncing message: " + e.getMessage());
         }
     }
 
     public String getMailetInfo() {
         return "RemoteDelivery Mailet";
     }
 
     /***
      * For this message, we take the list of recipients, organize these into distinct
      * servers, and duplicate the message for each of these servers, and then call
      * the deliver (messagecontainer) method for each server-specific
      * messagecontainer ... that will handle storing it in the outgoing queue if needed.
      *
      * @param mail org.apache.mailet.Mail
      */
     public void service(Mail mail) throws MessagingException{
         // Do I want to give the internal key, or the message's Message ID
         if (isDebug) {
             log("Remotely delivering mail " + mail.getName());
         }
         Collection recipients = mail.getRecipients();
 
         if (gatewayServer == null) {
             // Must first organize the recipients into distinct servers (name made case insensitive)
             Hashtable targets = new Hashtable();
             for (Iterator i = recipients.iterator(); i.hasNext();) {
                 MailAddress target = (MailAddress)i.next();
                 String targetServer = target.getHost().toLowerCase(Locale.US);
                 Collection temp = (Collection)targets.get(targetServer);
                 if (temp == null) {
                     temp = new ArrayList();
                     targets.put(targetServer, temp);
                 }
                 temp.add(target);
             }
 
             //We have the recipients organized into distinct servers... put them into the
             //delivery store organized like this... this is ultra inefficient I think...
 
             // Store the new message containers, organized by server, in the outgoing mail repository
             String name = mail.getName();
             for (Iterator i = targets.keySet().iterator(); i.hasNext(); ) {
                 String host = (String) i.next();
                 Collection rec = (Collection) targets.get(host);
                 if (isDebug) {
                     StringBuffer logMessageBuffer =
                         new StringBuffer(128)
                                 .append("Sending mail to ")
                                 .append(rec)
                                 .append(" on host ")
                                 .append(host);
                     log(logMessageBuffer.toString());
                 }
                 mail.setRecipients(rec);
                 StringBuffer nameBuffer =
                     new StringBuffer(128)
                             .append(name)
                             .append("-to-")
                             .append(host);
                 mail.setName(nameBuffer.toString());
                 outgoing.store(mail);
                 //Set it to try to deliver (in a separate thread) immediately (triggered by storage)
             }
         } else {
             // Store the mail unaltered for processing by the gateway server(s)
             if (isDebug) {
                 StringBuffer logMessageBuffer =
                     new StringBuffer(128)
                         .append("Sending mail to ")
                         .append(mail.getRecipients())
                         .append(" via ")
                         .append(gatewayServer);
                 log(logMessageBuffer.toString());
             }
 
              //Set it to try to deliver (in a separate thread) immediately (triggered by storage)
             outgoing.store(mail);
         }
         mail.setState(Mail.GHOST);
     }
 
     // Need to synchronize to get object monitor for notifyAll()
     public synchronized void destroy() {
         //Mark flag so threads from this mailet stop themselves
         destroyed = true;
         //Wake up all threads from waiting for an accept
         for (Iterator i = deliveryThreads.iterator(); i.hasNext(); ) {
             Thread t = (Thread)i.next();
             t.interrupt();
         }
         notifyAll();
     }
 
     /***
      * Handles checking the outgoing spool for new mail and delivering them if
      * there are any
      */
     public void run() {
 
         /* TODO: CHANGE ME!!! The problem is that we need to wait for James to
          * finish initializing.  We expect the HELLO_NAME to be put into
          * the MailetContext, but in the current configuration we get
          * started before the SMTP Server, which establishes the value.
          * Since there is no contractual guarantee that there will be a
          * HELLO_NAME value, we can't just wait for it.  As a temporary
          * measure, I'm inserting this philosophically unsatisfactory
          * fix.
          */
         long stop = System.currentTimeMillis() + 60000;
         while ((getMailetContext().getAttribute(Constants.HELLO_NAME) == null)
                && stop > System.currentTimeMillis()) {
             try {
                 Thread.sleep(1000);
             } catch (Exception ignored) {} // wait for James to finish initializing
         }
 
         //Checks the pool and delivers a mail message
         Properties props = new Properties();
         //Not needed for production environment
         props.put("mail.debug", "false");
         // Reactivated: javamail 1.3.2 should no more have problems with "250 OK"
         // messages (WAS "false": Prevents problems encountered with 250 OK Messages)
         props.put("mail.smtp.ehlo", "true");
         // By setting this property to true the transport is allowed to
         // send 8 bit data to the server (if it supports the 8bitmime extension).
         // 2006/03/01 reverted to false because of a javamail bug converting to 8bit
         // messages created by an inputstream.
         props.setProperty("mail.smtp.allow8bitmime", "false");
         //Sets timeout on going connections
         props.put("mail.smtp.timeout", smtpTimeout + "");
 
         props.put("mail.smtp.connectiontimeout", connectionTimeout + "");
         props.put("mail.smtp.sendpartial",String.valueOf(sendPartial));
 
         //Set the hostname we'll use as this server
         if (getMailetContext().getAttribute(Constants.HELLO_NAME) != null) {
             props.put("mail.smtp.localhost", getMailetContext().getAttribute(Constants.HELLO_NAME));
         }
         else {
             String defaultDomain = (String) getMailetContext().getAttribute(Constants.DEFAULT_DOMAIN);
             if (defaultDomain != null) {
                 props.put("mail.smtp.localhost", defaultDomain);
             }
         }
 
         if (isBindUsed) {
             // undocumented JavaMail 1.2 feature, smtp transport will use
             // our socket factory, which will also set the local address
             props.put("mail.smtp.socketFactory.class",
                       "org.apache.james.transport.mailets.RemoteDeliverySocketFactory");
             // Don't fallback to the standard socket factory on error, do throw an exception
             props.put("mail.smtp.socketFactory.fallback", "false");
         }
         
         if (authUser != null) {
             props.put("mail.smtp.auth","true");
         }
 
         Session session = Session.getInstance(props, null);
         try {
             while (!Thread.interrupted() && !destroyed) {
                 try {
                     Mail mail = (Mail)outgoing.accept(delayFilter);
                     String key = mail.getName();
                     try {
                         if (isDebug) {
                             StringBuffer logMessageBuffer =
                                 new StringBuffer(128)
                                         .append(Thread.currentThread().getName())
                                         .append(" will process mail ")
                                         .append(key);
                             log(logMessageBuffer.toString());
                         }
                         if (deliver(mail, session)) {
                             //Message was successfully delivered/fully failed... delete it
                             ContainerUtil.dispose(mail);
                             outgoing.remove(key);
                         } else {
                             //Something happened that will delay delivery.  Store any updates
                             outgoing.store(mail);
                             ContainerUtil.dispose(mail);
                             // This is an update, we have to unlock and notify or this mail
                             // is kept locked by this thread
                             outgoing.unlock(key);
                             // We do not notify because we updated an already existing mail
                             // and we are now free to handle more mails.
                             // Furthermore this mail should not be processed now because we
                             // have a retry time scheduling.
                         }
                         //Clear the object handle to make sure it recycles this object.
                         mail = null;
                     } catch (Exception e) {
                         // Prevent unexpected exceptions from causing looping by removing
                         // message from outgoing.
                         // DO NOT CHNANGE THIS to catch Error!  For example, if there were an OutOfMemory condition
                         // caused because something else in the server was abusing memory, we would not want to
                         // start purging the outgoing spool!
                         ContainerUtil.dispose(mail);
                         outgoing.remove(key);
                         throw e;
                     }
                 } catch (Throwable e) {
                     if (!destroyed) log("Exception caught in RemoteDelivery.run()", e);
                 }
             }
         } finally {
             // Restore the thread state to non-interrupted.
             Thread.interrupted();
         }
     }
 
     /***
      * @param list holding Delay objects
      * @return the total attempts for all delays
      **/
     private int calcTotalAttempts (ArrayList list) {
         int sum = 0;
         Iterator i = list.iterator();
         while (i.hasNext()) {
             Delay delay = (Delay)i.next();
             sum += delay.getAttempts();
         }
         return sum;
     }
     
     /***
      * This method expands an ArrayList containing Delay objects into an array holding the
      * only delaytime in the order.<p>
      * So if the list has 2 Delay objects the first having attempts=2 and delaytime 4000
      * the second having attempts=1 and delaytime=300000 will be expanded into this array:<p>
      * long[0] = 4000<p>
      * long[1] = 4000<p>
      * long[2] = 300000<p>
      * @param list the list to expand
      * @return the expanded list
      **/
     private long[] expandDelays (ArrayList list) {
         long[] delays = new long [calcTotalAttempts(list)];
         Iterator i = list.iterator();
         int idx = 0;
         while (i.hasNext()) {
             Delay delay = (Delay)i.next();
             for (int j=0; j<delay.getAttempts(); j++) {
                 delays[idx++]= delay.getDelayTime();
             }            
         }
         return delays;
     }
     
     /***
      * This method returns, given a retry-count, the next delay time to use.
      * @param retry_count the current retry_count.
      * @return the next delay time to use, given the retry count
      **/
     private long getNextDelay (int retry_count) {
         if (retry_count > delayTimes.length) {
             return DEFAULT_DELAY_TIME;
         } 
         return delayTimes[retry_count-1];
     }
 
     /***
      * This class is used to hold a delay time and its corresponding number
      * of retries.
      **/
     private class Delay {
         private int attempts = 1;
         private long delayTime = DEFAULT_DELAY_TIME;
         
             
         /***
          * This constructor expects Strings of the form "[attempt\*]delaytime[unit]". <p>
          * The optional attempt is the number of tries this delay should be used (default = 1)
          * The unit if present must be one of (msec,sec,minute,hour,day) (default = msec)
          * The constructor multiplies the delaytime by the relevant multiplier for the unit,
          * so the delayTime instance variable is always in msec.
          * @param init_string the string to initialize this Delay object from
          **/
         public Delay (String init_string) throws MessagingException
         {
             String unit = "msec"; //default unit
             if (delayTimeMatcher.matches (init_string, PATTERN)) {
                 MatchResult res = delayTimeMatcher.getMatch ();
                 //the capturing groups will now hold
                 //at 1:  attempts * (if present)
                 //at 2:  delaytime
                 //at 3:  unit (if present)
                 
                 if (res.group(1) != null && !res.group(1).equals ("")) {
                     //we have an attempt *
                     String attempt_match = res.group(1);
                     //strip the * and whitespace
                     attempt_match = attempt_match.substring (0,attempt_match.length()-1).trim();
                     attempts = Integer.parseInt (attempt_match);
                 }
                 
                 delayTime = Long.parseLong (res.group(2));
                 
                 if (!res.group(3).equals ("")) {
                     //we have a unit
                     unit = res.group(3).toLowerCase(Locale.US);
                 }
             } else {
                 throw new MessagingException(init_string+" does not match "+PATTERN_STRING);
             }
             if (MULTIPLIERS.get (unit)!=null) {
                 int multiplier = ((Integer)MULTIPLIERS.get (unit)).intValue();
                 delayTime *= multiplier;
             } else {
                 throw new MessagingException("Unknown unit: "+unit);
             }
         }
 
         /***
          * This constructor makes a default Delay object, ie. attempts=1 and delayTime=DEFAULT_DELAY_TIME
          **/
         public Delay () {
         }
 
         /***
          * @return the delayTime for this Delay
          **/
         public long getDelayTime () {
             return delayTime;
         }
 
         /***
          * @return the number attempts this Delay should be used.
          **/
         public int getAttempts () {
             return attempts;
         }
         
         /***
          * Set the number attempts this Delay should be used.
          **/
         public void setAttempts (int value) {
             attempts = value;
         }
         
         /***
          * Pretty prints this Delay 
          **/
         public String toString () {
             StringBuffer buf = new StringBuffer(15);
             buf.append (getAttempts ());
             buf.append ('*');
             buf.append (getDelayTime());
             buf.append ("msec");
             return buf.toString();
         }
     }
     
     /*
      * Returns an Iterator over org.apache.mailet.HostAddress, a
      * specialized subclass of javax.mail.URLName, which provides
      * location information for servers that are specified as mail
      * handlers for the given hostname.  If no host is found, the
      * Iterator returned will be empty and the first call to hasNext()
      * will return false.  The Iterator is a nested iterator: the outer
      * iteration is over each gateway, and the inner iteration is over
      * potentially multiple A records for each gateway.
      *
      * @see org.apache.james.DNSServer#getSMTPHostAddresses(String)
      * @since v2.2.0a16-unstable
      * @param gatewayServers - Collection of host[:port] Strings
      * @return an Iterator over HostAddress instances, sorted by priority
      */
     private Iterator getGatewaySMTPHostAddresses(final Collection gatewayServers) {
         return new Iterator() {
             private Iterator gateways = gatewayServers.iterator();
             private Iterator addresses = null;
 
             public boolean hasNext() {
                 /* Make sure that when next() is called, that we can
                  * provide a HostAddress.  This means that we need to
                  * have an inner iterator, and verify that it has
                  * addresses.  We could, for example, run into a
                  * situation where the next gateway didn't have any
                  * valid addresses.
                  */
                 if (!hasNextAddress() && gateways.hasNext()) {
                     do {
                         String server = (String) gateways.next();
                         String port = "25";
 
                         int idx = server.indexOf(':');
                         if ( idx > 0) {
                             port = server.substring(idx+1);
                             server = server.substring(0,idx);
                         }
 
                         final String nextGateway = server;
                         final String nextGatewayPort = port;
                         try {
                             final InetAddress[] ips = org.apache.james.dnsserver.DNSServer.getAllByName(nextGateway);
                             addresses = new Iterator() {
                                 private InetAddress[] ipAddresses = ips;
                                 int i = 0;
 
                                 public boolean hasNext() {
                                     return i < ipAddresses.length;
                                 }
 
                                 public Object next() {
                                     return new org.apache.mailet.HostAddress(nextGateway, "smtp://" + (ipAddresses[i++]).getHostAddress() + ":" + nextGatewayPort);
                                 }
 
                                 public void remove() {
                                     throw new UnsupportedOperationException ("remove not supported by this iterator");
                                 }
                             };
                         }
                         catch (java.net.UnknownHostException uhe) {
                             log("Unknown gateway host: " + uhe.getMessage().trim());
                             log("This could be a DNS server error or configuration error.");
                         }
                     } while (!hasNextAddress() && gateways.hasNext());
                 } 
 
                 return hasNextAddress();
             }
 
             private boolean hasNextAddress() {
                 return addresses != null && addresses.hasNext();
             }
 
             public Object next() {
                 return (addresses != null) ? addresses.next() : null;
             }
 
             public void remove() {
                 throw new UnsupportedOperationException ("remove not supported by this iterator");
             }
         };
     }
 }