// Nnrpd - multi-threaded proxying NNRP daemon
//
// Copyright (C) 1996 by Jef Poskanzer <jef@mail.acme.com>.  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/

package Acme.Nnrpd;

import java.io.*;
import java.util.*;
import java.net.*;
import Acme.Utils;
import Acme.Fmt;
import Acme.Syslog;
import Acme.SyslogException;
import Acme.TimeKiller;

/// Multi-threaded proxying NNRP daemon.
// <P>
// This is a replacement for the standard C nnrpd.  Sites with lots
// of readers have found that running a separate nnrpd for each reader
// puts a tremendous load on the system.  All that memory, all those
// context switches.  This solves both problems by having a single
// process service multiple readers simultaneously.
// <P>
// Optionally, you can also use this as an NNRP proxy, connecting to
// a remote nnrpd instead of getting articles from the local disk.
// <P>
// Logging is via syslog, and is compatible with the standard nnrpd logging.
// <P>
// <A HREF="/resources/classes/Acme/Nnrpd/Nnrpd.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>

public class Nnrpd
    {

    private static final String progName = "Nnrpd";

    /// Main routine, if you want to run this directly as an application.
    public static void main( String[] args )
	{
	// Parse args.
	int port = NnrpdUtils.DEFAULT_PORT;
	int aCacheSize = NnrpdUtils.DEFAULT_ACACHESIZE;
	int maxArtSize = NnrpdUtils.DEFAULT_MAXARTSIZE;
	int oCacheSize = NnrpdUtils.DEFAULT_OCACHESIZE;
	String proxyHost = null;
	boolean debug = false;
	int argc = args.length;
	int argn;
	for ( argn = 0; argn < argc && args[argn].charAt( 0 ) == '-'; ++argn )
	    {
	    if ( args[argn].equals( "-p" ) && argn + 1 < argc )
		{
		++argn;
		port = Utils.parseInt( args[argn], -1 );
		if ( port == -1 )
		    usage();
		}
	    else if ( args[argn].equals( "-a" ) && argn + 1 < argc )
		{
		++argn;
		aCacheSize = Utils.parseInt( args[argn], -1 );
		if ( aCacheSize == -1 )
		    usage();
		}
	    else if ( args[argn].equals( "-o" ) && argn + 1 < argc )
		{
		++argn;
		oCacheSize = Utils.parseInt( args[argn], -1 );
		if ( oCacheSize == -1 )
		    usage();
		}
	    else if ( args[argn].equals( "-h" ) && argn + 1 < argc )
		{
		++argn;
		proxyHost = args[argn];
		}
	    else if ( args[argn].equals( "-d" ) )
		debug = true;
	    else
		usage();
	    }
	if ( argn != argc )
	    usage();

	try
	    {
	    // Create the server.
	    Nnrpd nnrpd = new Nnrpd(
		port, aCacheSize, maxArtSize, oCacheSize, proxyHost, debug );

	    // And run.
	    nnrpd.serve();
	    }
	catch ( NnrpdException e )
	    {
	    System.err.println( e );
	    System.exit( 1 );
	    }

	System.exit( 0 );
	}

    private static void usage()
	{
	System.err.println(
	    "usage:  " + progName +
	    " [-p port] [-a art-cachesize] [-o ov-cachesize] [-h proxyhost]" );
	System.err.println( "" );
	System.err.println( "  port:" );
	System.err.println(
	    "    Normally netnews servers run on port " + NnrpdUtils.DEFAULT_PORT + ", which is where the" );
	System.err.println(
	    "    readers look for them.  You can run this on a different port if" );
	System.err.println(
	    "    you like, perhaps for debugging." );
	System.err.println( "  art-cachesize:" );
	System.err.println( "    How many bytes of articles to cache.  Default is " + NnrpdUtils.DEFAULT_ACACHESIZE + "." );
	System.err.println( "  ov-cachesize:" );
	System.err.println(
	    "    How many overview entries to cache.  Default is " + NnrpdUtils.DEFAULT_OCACHESIZE + "." );
	System.err.println( "  proxyhost:" );
	System.err.println(
	    "    The remote news server to connect to, for proxy mode.  Syntax" );
	System.err.println(
	    "    is a hostname, or hostname:port for ports other than " + NnrpdUtils.DEFAULT_PORT + "." );
	System.err.println( "" );
	System.err.println( "For more information see the web page," );
	System.err.println( NnrpdUtils.serverUrl );
	System.exit( 1 );
	}


    private int port;
    private int aCacheSize;
    private int maxArtSize;
    private int oCacheSize;
    private String proxyHost;
    private boolean debug;

    private Syslog syslog;
    private NewsDb newsDb;
    private ArticleCache articleCache;
    private boolean newsDbPostingOk;

    /// Constructor.
    // @param port Normally netnews servers run on port 119, which is where the readers look for them.  You can run this on a different port if you like, perhaps for debugging.
    // @param aCacheSize How many bytes of articles to cache.
    // @param maxArtSize Articles larger than this do not get cached at all.
    // @param oCacheSize How many overview entries to cache.
    // @param proxyHost The remote news server to connect to, for proxy mode.  Syntax is a hostname, or hostname:port for ports other than 119.
    // @param debug Whether to emit debugging syslogs or just dump them.
    // @exception NnrpdException if something goes wrong
    public Nnrpd( int port, int aCacheSize, int maxArtSize, int oCacheSize, String proxyHost, boolean debug ) throws NnrpdException
	{
	this.port = port;
	this.aCacheSize = aCacheSize;
	this.maxArtSize = maxArtSize;
	this.oCacheSize = oCacheSize;
	this.proxyHost = proxyHost;
	this.debug = debug;

	try
	    {
	    syslog = new Syslog( progName, 0, Syslog.LOG_NEWS );
	    }
	catch ( SyslogException e )
	    {
	    throw new NnrpdException( "can't initialize syslog: " + e );
	    }

	articleCache = new ArticleCache( aCacheSize, maxArtSize );

	try
	    {
	    if ( proxyHost != null )
		newsDb = new ProxyNewsDb( proxyHost, oCacheSize );
	    else
		newsDb = new LocalNewsDb( oCacheSize );
	    newsDbPostingOk = newsDb.getPostingOk();
	    }
	catch ( NewsDbException e )
	    {
	    throw new NnrpdException( "problem initializing news db: " + e );
	    }
	}


    /// Run the server.  Returns only on errors.
    // @exception NnrpdException if something goes wrong
    public void serve() throws NnrpdException
	{
	ServerSocket serverSocket;
	try
	    {
	    serverSocket = new ServerSocket( port, 1000 );
	    }
	catch ( IOException e )
	    {
	    error( "problem getting server socket: " + e );
	    return;
	    }

	try
	    {
	    while ( true )
		{
		try
		    {
		    Socket socket = serverSocket.accept();
		    new NnrpdSession(
			this, newsDb, newsDbPostingOk, articleCache, socket );
		    }
		catch ( IOException e )
		    {
		    if ( ! e.getMessage().endsWith( "Interrupted system call" ) )
			throw e;
		    }
		}
	    }
	catch ( IOException e )
	    {
	    error( "problem doing accept: " + e );
	    }
	finally
	    {
	    try
		{
		serverSocket.close();
		}
	    catch ( IOException ignore ) {}
	    }
	}


    void debug( String message ) throws NnrpdException
	{
	if ( debug )
	    log( Syslog.LOG_DEBUG, message );
	}

    void info( String message ) throws NnrpdException
	{
	log( Syslog.LOG_INFO, message );
	}

    void notice( String message ) throws NnrpdException
	{
	log( Syslog.LOG_NOTICE, message );
	}

    void warning( String message ) throws NnrpdException
	{
	log( Syslog.LOG_WARNING, message );
	}

    void error( String message ) throws NnrpdException
	{
	log( Syslog.LOG_ERR, message );
	}

    void crit( String message ) throws NnrpdException
	{
	log( Syslog.LOG_CRIT, message );
	}

    void alert( String message ) throws NnrpdException
	{
	log( Syslog.LOG_ALERT, message );
	}

    void emerg( String message ) throws NnrpdException
	{
	log( Syslog.LOG_EMERG, message );
	}

    private void log( int priority, String message ) throws NnrpdException
	{
	try
	    {
	    syslog.syslog( priority, message );
	    }
	catch ( SyslogException e )
	    {
	    throw new NnrpdException( "syslog problem: " + e );
	    }
	}

    }


class NnrpdSession implements Runnable
    {

    /// The overview.fmt we implement.  It seems that some netnews user agents
    // just assume this format, rather than asking the backend what format
    // it provides.  Therefore we hardcode the format.
    private static String[] overviewFmt = {
	"Subject", "From", "Date", "Message-ID", "References", "Bytes",
	"Lines" };

    private Nnrpd nnrpd;
    private NewsDb newsDb;
    private boolean newsDbPostingOk;
    private ArticleCache articleCache;
    private Socket socket;
    private String clientHost;

    /// Constructor.
    public NnrpdSession( Nnrpd nnrpd, NewsDb newsDb, boolean newsDbPostingOk, ArticleCache articleCache, Socket socket )
	{
	// Save arguments.
	this.nnrpd = nnrpd;
	this.newsDb = newsDb;
	this.newsDbPostingOk = newsDbPostingOk;
	this.articleCache = articleCache;
	this.socket = socket;

	// Start a thread.
	Thread thread = new Thread( this );
	thread.start();
	}

    private DataInputStream din;
    private PrintStream pout;

    public void run()
	{
	try
	    {
	    clientHost = socket.getInetAddress().getHostName();
	    notice( clientHost + " connect" );
	    try
		{
		// Get the streams.
		din = new DataInputStream( new BufferedInputStream(
		    socket.getInputStream() ) );
		pout = new PrintStream( new CrLfOutputStream(
		    new BufferedOutputStream( socket.getOutputStream() ) ) );
		}
	    catch ( IOException e )
		{
		warning( clientHost + " problem getting streams: " + e );
		return;
		}

	    handleSession();

	    try
		{
		din.close();
		pout.flush();
		pout.close();
		socket.close();
		}
	    catch ( IOException ignore ) {}
	    }
	catch ( NnrpdException e )
	    {
	    System.err.println( "uncaught exception: " + e );
	    }
	}


    /// Read and handle requests until done.
    private void handleSession() throws NnrpdException
	{
	if ( newsDbPostingOk )
	    response(
		"200 " + NnrpdUtils.serverName + " " +
		NnrpdUtils.serverVersion + " ready - posting allowed" );
	else
	    response(
		"201 " + NnrpdUtils.serverName + " " +
		NnrpdUtils.serverVersion + " ready - no posting allowed" );

	TimeKiller tk = new TimeKiller( NnrpdUtils.INT_IDLETIMEOUT );
	while ( true )
	    {
	    // Flush previous output.
	    pout.flush();
	    // Reset idle timer.
	    tk.reset();
	    // Read a command line.
	    String commandLine;
	    try
		{
		commandLine = din.readLine();
		}
	    catch ( IOException e )
		{
		warning( clientHost + " problem reading command: " + e );
		break;
		}
	    debug( clientHost + " < " + commandLine );
	    try
		{
		if ( commandLine == null )
		    {
		    // End of file - treat as a QUIT.
		    cmdQuit( null );
		    break;
		    }

		// Split up the command word and the rest of the line.
		int ws = Utils.strCSpan( commandLine, " \t" );
		String command = commandLine.substring( 0, ws );
		String[] args =
		    Utils.splitStr( commandLine.substring( ws ).trim() );

		// Dispatch the command to the right subroutine.
		if ( command.equalsIgnoreCase( NnrpdUtils.CMD_ARTICLE ) )
		    cmdArticle( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_AUTHINFO ) )
		    cmdAuthinfo( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_BODY ) )
		    cmdBody( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_DATE ) )
		    cmdDate( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_GROUP ) )
		    cmdGroup( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_HEAD ) )
		    cmdHead( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_HELP ) )
		    cmdHelp( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_LAST ) )
		    cmdLast( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_LIST ) )
		    cmdList( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_LISTGROUP ) )
		    cmdListgroup( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_MODE ) ||
		          command.equalsIgnoreCase( NnrpdUtils.CMD_XMODE ) )
		    cmdMode( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_NEWGROUPS ) )
		    cmdNewgroups( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_NEWNEWS ) )
		    cmdNewnews( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_NEXT ) )
		    cmdNext( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_POST ) )
		    cmdPost( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_QUIT ) )
		    {
		    cmdQuit( args );
		    break;
		    }
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_SLAVE ) )
		    cmdSlave( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_STAT ) )
		    cmdStat( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_XGTITLE ) )
		    cmdXgtitle( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_XHDR ) )
		    cmdXhdr( args );
		else if ( command.equalsIgnoreCase( NnrpdUtils.CMD_XOVER ) )
		    cmdXover( args );
		else
		    {
		    notice( clientHost + " unrecognized " + commandLine );
		    response( NnrpdUtils.RES_BADCOMMAND );
		    }
		}
	    catch ( NewsDbException e )
		{
		warning( clientHost + " " + e );
		response( NnrpdUtils.RES_PROGFAULT + ": " + e );
		}
	    catch ( NnrpdException e )
		{
		warning( clientHost + " " + e );
		response( NnrpdUtils.RES_PROGFAULT + ": " + e );
		}
	    }
	tk.done();
	}


    // State variables.
    private NewsDbGroup currentGroup = null;
    private int currentArtNum = -1;

    // Stats variables.
    private long startTime = System.currentTimeMillis();
    private int groupCount = 0;
    private int artCount = 0;
    private int postsOk = 0;
    private int postsBad = 0;
    private int groupArts;


    // Command routines.

    private void cmdArticle( String[] args ) throws NewsDbException, NnrpdException
	{
	cmdAhbs( args, 'a' );
	}

    private String user = null;
    private String pass = null;

    private void cmdAuthinfo( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 2 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	if ( args[0].equalsIgnoreCase( "user" ) )
	    {
	    user = args[1];
	    response( "381 AUTHINFO PASS required" );
	    }
	else if ( args[0].equalsIgnoreCase( "pass" ) )
	    {
	    if ( user == null )
		response( "482 AUTHINFO USER required" );
	    else
		{
		if ( newsDb.authorize( user, pass ) )
		    response( "281 authentication ok" );
		else
		    response( "502 authentication failed" );
		}
	    }
	else
	    response( NnrpdUtils.RES_SYNTAXERROR );
	}

    private void cmdBody( String[] args ) throws NewsDbException, NnrpdException
	{
	cmdAhbs( args, 'b' );
	}

    private void cmdDate( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 0 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	Date date = new Date();
	String gmtStr = date.toGMTString();
	String[] strArr = Utils.splitStr( gmtStr );
	int day = Integer.parseInt( strArr[0] );
	String months = "JanFebMarAprMayJunJulAugSepOctNovDec";
	int month = months.indexOf( strArr[1] ) / 3 + 1;
	int year = Integer.parseInt( strArr[2] );
	int hour = Integer.parseInt( strArr[3].substring( 0, 2 ) );
	int minute = Integer.parseInt( strArr[3].substring( 3, 5 ) );
	int second = Integer.parseInt( strArr[3].substring( 6, 8 ) );
	response( "111 " +
	    Fmt.fmt( year, 4, Fmt.ZF ) +
	    Fmt.fmt( month, 2, Fmt.ZF ) +
	    Fmt.fmt( day, 2, Fmt.ZF ) +
	    Fmt.fmt( hour, 2, Fmt.ZF ) +
	    Fmt.fmt( minute, 2, Fmt.ZF ) +
	    Fmt.fmt( second, 2, Fmt.ZF ) );
	}

    private void cmdGroup( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 1 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	NewsDbGroup group = newsDb.getGroup( args[0] );
	if ( group == null )
	    response( NnrpdUtils.RES_NOSUCHGROUP );
	else
	    {
	    groupLog();
	    currentGroup = group;
	    currentArtNum = currentGroup.getFirstArtNum();
	    response( "211 " +
		currentGroup.getNumArts() + " " +
		currentArtNum + " " +
		currentGroup.getLastArtNum() + " " +
		currentGroup.getName() );
	    }
	}

    private void cmdHead( String[] args ) throws NewsDbException, NnrpdException
	{
	cmdAhbs( args, 'h' );
	}

    private void cmdHelp( String[] args ) throws NewsDbException, NnrpdException
	{
	response( "100 help text follows" );
	pout.println( "ARTICLE [<messageid>|number]" );
	pout.println( "AUTHINFO user name|pass password" );
	pout.println( "BODY [<messageid>|number]" );
	pout.println( "DATE" );
	pout.println( "GROUP newsgroup" );
	pout.println( "HEAD [<messageid>|number]" );
	pout.println( "HELP" );
	pout.println( "LAST" );
	pout.println( "LIST [active|newsgroups|distributions|schema] [group_pattern]" );
	pout.println( "LISTGROUP newsgroup" );
	pout.println( "MODE reader" );
	pout.println( "NEWGROUPS yymmdd hhmmss [GMT] [distributions]" );
	pout.println( "NEWNEWS newsgroups yymmdd hhmmss [GMT] [distributions]" );
	pout.println( "NEXT" );
	pout.println( "POST" );
	pout.println( "QUIT" );
	pout.println( "SLAVE" );
	pout.println( "STAT [<messageid>|number]" );
	pout.println( "XGTITLE [group_pattern]" );
	pout.println( "XHDR header [range|<messageid>]" );
	pout.println( "XOVER [range]" );
	pout.println( "." );
	}

    private void cmdLast( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 0 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	if ( currentGroup == null )
	    response( NnrpdUtils.RES_NOCURRGROUP );
	else if ( currentArtNum == -1 )
	    response( NnrpdUtils.RES_NOCURRARTICLE );
	else
	    {
	    int artNum = currentArtNum;
	    while ( --artNum >= currentGroup.getFirstArtNum() )
		{
		NewsDbArticle article = getArticle( currentGroup, artNum );
		if ( article == null )
		    continue;
		currentArtNum = artNum;
		sendAhbs( article, currentArtNum, 's' );
		return;
		}
	    response( "422 no previous article in this group" );
	    }
	}

    private void cmdList( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length > 2 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	if ( args.length == 0 || args[0].equalsIgnoreCase( "active" ) )
	    {
	    response( "215 list of newsgroups follows" );
	    Enumeration en = newsDb.getGroups();
	    while ( en.hasMoreElements() )
		{
		NewsDbGroup group = (NewsDbGroup) en.nextElement();
		if ( args.length == 2 &&
		     ! Utils.match( args[1], group.getName() ) )
		    continue;
		sendGroup( group );
		}
	    pout.println( "." );
	    }
	else if ( args[0].equalsIgnoreCase( "active.times" ) )
	    {
	    response( NnrpdUtils.RES_UNIMPLEMENTED );
	    }
	else if ( args[0].equalsIgnoreCase( "newsgroups" ) )
	    {
	    response( "215 list of descriptions follows" );
	    Enumeration en = newsDb.getGroups();
	    while ( en.hasMoreElements() )
		{
		NewsDbGroup group = (NewsDbGroup) en.nextElement();
		String groupName = group.getName();
		if ( args.length == 2 &&
		     ! Utils.match( args[1], groupName ) )
		    continue;
		String description = group.getDescription();
		if ( description != null )
		    pout.println( groupName + "\t" + group.getDescription() );
		}
	    pout.println( "." );
	    }
	else if ( args[0].equalsIgnoreCase( "distributions" ) )
	    {
	    response( NnrpdUtils.RES_UNIMPLEMENTED );
	    }
	else if ( args[0].equalsIgnoreCase( "distrib.pats" ) )
	    {
	    response( NnrpdUtils.RES_UNIMPLEMENTED );
	    }
	else if ( args[0].equalsIgnoreCase( "schema" ) ||
	          args[0].equalsIgnoreCase( "overview.fmt" ) )
	    {
	    response( "215 Order of fields in overview database" );
	    for ( int i = 0; i < overviewFmt.length; ++i )
		pout.println( overviewFmt[i] + ":" );
	    pout.println( "." );
	    }
	else
	    response( NnrpdUtils.RES_SYNTAXERROR );
	}

    private void cmdListgroup( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 1 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	NewsDbGroup group = newsDb.getGroup( args[0] );
	if ( group == null )
	    response( NnrpdUtils.RES_NOSUCHGROUP );
	else
	    {
	    groupLog();
	    currentGroup = group;
	    currentArtNum = currentGroup.getFirstArtNum();
	    response( "211 article list follows" );
	    // We're going to do the cheap thing here and just count from
	    // the first article to the last article.
	    for ( int artNum = currentGroup.getFirstArtNum();
		  artNum <= currentGroup.getLastArtNum(); ++artNum )
		pout.println( artNum );
	    pout.println( "." );
	    }
	}

    private void cmdMode( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 1 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	if ( args[0].equalsIgnoreCase( "reader" ) )
	    response( "200 reading mode acknowledged" );
	else
	    response( NnrpdUtils.RES_SYNTAXERROR );
	}

    private void cmdNewgroups( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length < 2 || args.length > 4 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	String date = args[0];
	String time = args[1];
	boolean gmt = false;
	String distsPat = null;
	if ( args.length >= 3 )
	    if ( args[2].equalsIgnoreCase( "GMT" ) )
		{
		gmt = true;
		if ( args.length == 4 )
		    distsPat = args[3];
		}
	    else
		{
		if ( args.length == 4 )
		    {
		    response( NnrpdUtils.RES_SYNTAXERROR );
		    return;
		    }
		distsPat = args[4];
		}
	long since = NnrpdUtils.rfc977DateTime( date, time, gmt, -1 );
	if ( since == -1 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	response( "231 list of new newsgroups follows" );
	Enumeration en;
	if ( distsPat == null )
	    en = newsDb.getGroups( since );
	else
	    en = newsDb.getGroups( since, distsPat );
	while ( en.hasMoreElements() )
	    {
	    NewsDbGroup group = (NewsDbGroup) en.nextElement();
	    sendGroup( group );
	    }
	pout.println( "." );
	}

    private void cmdNewnews( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length < 3 || args.length > 5 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	String groupsPat = args[0];
	String date = args[1];
	String time = args[2];
	boolean gmt = false;
	String distsPat = null;
	if ( args.length >= 4 )
	    if ( args[3].equalsIgnoreCase( "GMT" ) )
		{
		gmt = true;
		if ( args.length == 5 )
		    distsPat = args[4];
		}
	    else
		{
		if ( args.length == 5 )
		    {
		    response( NnrpdUtils.RES_SYNTAXERROR );
		    return;
		    }
		distsPat = args[5];
		}
	long since = NnrpdUtils.rfc977DateTime( date, time, gmt, -1 );
	if ( since == -1 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	notice(
	    clientHost + " newnews " + groupsPat + " " +
	    date + " " + time + " " + ( gmt ? "GMT" : "local" ) +
	    ( distsPat != null ? distsPat : "none" ) );
	response( "230 list of new articles by message-id follows" );
	Enumeration en;
	if ( distsPat == null )
	    en = newsDb.getMessageIds( groupsPat, since );
	else
	    en = newsDb.getMessageIds( groupsPat, since, distsPat );
	while ( en.hasMoreElements() )
	    {
	    String messageId = (String) en.nextElement();
	    pout.println( messageId );
	    }
	pout.println( "." );
	}

    private void cmdNext( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 0 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	if ( currentGroup == null )
	    response( NnrpdUtils.RES_NOCURRGROUP );
	else if ( currentArtNum == -1 )
	    response( NnrpdUtils.RES_NOCURRARTICLE );
	else
	    {
	    int artNum = currentArtNum;
	    while ( ++artNum <= currentGroup.getLastArtNum() )
		{
		NewsDbArticle article = getArticle( currentGroup, artNum );
		if ( article == null )
		    continue;
		currentArtNum = artNum;
		sendAhbs( article, currentArtNum, 's' );
		return;
		}
	    response( "421 no next article in this group" );
	    }
	}

    private void cmdPost( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 0 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	if ( ! newsDb.getPostingOk() )
	    {
	    notice( clientHost + " noperm post without permission" );
	    response( "440 posting not allowed" );
	    return;
	    }
	response( "340 send article to be posted. End with <CR-LF>.<CR-LF>" );
	pout.flush();
	String text;
	try
	    {
	    text = NnrpdUtils.readText( din );
	    }
	catch ( IOException e )
	    {
	    warning( clientHost + "problem reading post: " + e );
	    ++postsBad;
	    response( "441 posting failed: " + e );
	    return;
	    }
	try
	    {
	    newsDb.post( text );
	    notice( clientHost + " post ok" );
	    ++postsOk;
	    response( "240 article posted ok" );
	    }
	catch ( NewsDbException e )
	    {
	    notice( clientHost + " post failed: " + e );
	    ++postsBad;
	    response( "441 posting failed: " + e );
	    }
	}

    private void cmdSlave( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length != 0 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	response( "202 slave status noted" );
	}

    private void cmdQuit( String[] args ) throws NewsDbException, NnrpdException
	{
	sessionLog();
	response( "205 closing connection - goodbye!" );
	}

    private void cmdStat( String[] args ) throws NewsDbException, NnrpdException
	{
	cmdAhbs( args, 's' );
	}

    private void cmdXgtitle( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length > 1 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	String groupsPat;
	if ( args.length == 1 )
	    groupsPat = args[0];
	else
	    {
	    if ( currentGroup == null )
		{
		response( NnrpdUtils.RES_NOCURRGROUP );
		return;
		}
	    groupsPat = currentGroup.getName();
	    }
	response( "282 list follows" );
	Enumeration en = newsDb.getGroups();
	while ( en.hasMoreElements() )
	    {
	    NewsDbGroup group = (NewsDbGroup) en.nextElement();
	    String groupName = group.getName();
	    if ( Utils.match( groupsPat, groupName ) )
		{
		String description = group.getDescription();
		if ( description != null )
		    pout.println( groupName + "\t" + group.getDescription() );
		}
	    }
	pout.println( "." );
	}

    private void cmdXhdr( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length < 1 || args.length > 2 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	String header = args[0];
	if ( args.length == 1 )
	    {
	    // Use current article.
	    if ( currentGroup == null )
		response( NnrpdUtils.RES_NOCURRGROUP );
	    else if ( currentArtNum == -1 )
		response( NnrpdUtils.RES_NOCURRARTICLE );
	    else
		sendXhdrRange( currentArtNum, currentArtNum, header );
	    }
	else if ( args[1].charAt( 0 ) == '<' )
	    {
	    // By message-id.
	    String messageId = args[1];
	    NewsDbArticle article = getArticle( messageId );
	    if ( article == null )
		response( NnrpdUtils.RES_NOSUCHARTICLE );
	    else
		{
		response(
		    "221 " + header + " header of article " + messageId );
		sendXhdrLine( article, header, messageId );
		pout.println( "." );
		}
	    }
	else
	    {
	    int[] range = parseRange( args[1] );
	    if ( range == null )
		response( NnrpdUtils.RES_SYNTAXERROR );
	    else
		sendXhdrRange( range[0], range[1], header );
	    }
	}
    
    private void sendXhdrRange( int firstArtNum, int lastArtNum, String header ) throws NewsDbException, NnrpdException
	{
	response( "221 " + header + " fields follow" );
	for ( int artNum = firstArtNum; artNum <= lastArtNum; ++artNum )
	    {
	    NewsDbArticle article = getArticle( currentGroup, artNum );
	    if ( article != null )
		sendXhdrLine( article, header, Integer.toString( artNum ) );
	    }
	pout.println( "." );
	}

    private void sendXhdrLine( NewsDbArticle article, String header, String ident )
	{
	String val = article.getHeader( header );
	if ( val == null )
	    pout.println( ident + " (none)" );
	else
	    pout.println( ident + " " + val );
	}

    private void cmdXover( String[] args ) throws NewsDbException, NnrpdException
	{
	if ( args.length > 1 )
	    {
	    response( NnrpdUtils.RES_SYNTAXERROR );
	    return;
	    }
	if ( args.length == 0 )
	    {
	    // Use current article.
	    if ( currentGroup == null )
		response( NnrpdUtils.RES_NOCURRGROUP );
	    else if ( currentArtNum == -1 )
		response( NnrpdUtils.RES_NOCURRARTICLE );
	    else
		sendXoverRange( currentGroup, currentArtNum, currentArtNum );
	    }
	else
	    {
	    int[] range = parseRange( args[0] );
	    if ( range == null )
		response( NnrpdUtils.RES_SYNTAXERROR );
	    else
		sendXoverRange( currentGroup, range[0], range[1] );
	    }
	}
    
    private void sendXoverRange( NewsDbGroup group, int firstArtNum, int lastArtNum ) throws NewsDbException, NnrpdException
	{
	int numArts = lastArtNum - firstArtNum + 1;
	String[][] results =
	    newsDb.getHeaders( overviewFmt, group, firstArtNum, lastArtNum );
	if ( results == null )
	    {
	    // Fall back on conventional weapons.
	    results = new String[numArts][overviewFmt.length];
	    for ( int i = 0; i < numArts; ++i )
		{
		int artNum = firstArtNum + i;
		NewsDbArticle article = getArticle( group, artNum );
		if ( article != null )
		    for ( int j = 0; j < overviewFmt.length; ++j )
			results[i][j] = article.getHeader( overviewFmt[j] );
		}
	    }
	response( "224 data follows" );
	for ( int i = 0; i < numArts; ++i )
	    {
	    if ( results[i] == null )
		continue;	// non-existent article
	    int artNum = firstArtNum + i;
	    StringBuffer buf = new StringBuffer();
	    buf.append( Integer.toString( artNum ) );
	    for ( int j = 0; j < overviewFmt.length; ++j )
		{
		buf.append( '\t' );
		buf.append( results[i][j] );
		}
	    pout.println( buf.toString() );
	    }
	pout.println( "." );
	}

    private void cmdAhbs( String[] args, char which ) throws NewsDbException, NnrpdException
	{
	if ( args.length == 0 )
	    if ( currentArtNum == -1 )
		response( NnrpdUtils.RES_NOCURRARTICLE );
	    else
		cmdAhbsNum( currentArtNum, which );
	else if ( args.length > 1 )
	    response( NnrpdUtils.RES_SYNTAXERROR );
	else if ( args[0].charAt( 0 ) == '<' )
	    cmdAhbsId( args[0], which );
	else
	    {
	    int artNum = Utils.parseInt( args[0], -1 );
	    if ( artNum == -1 )
		{
		response( NnrpdUtils.RES_SYNTAXERROR );
		return;
		}
	    cmdAhbsNum( artNum, which );
	    }
	}

    private void cmdAhbsNum( int artNum, char which ) throws NewsDbException, NnrpdException
	{
	if ( currentGroup == null )
	    response( NnrpdUtils.RES_NOCURRGROUP );
	else
	    {
	    NewsDbArticle article = getArticle( currentGroup, artNum );
	    if ( article == null )
		{
		response( NnrpdUtils.RES_NOSUCHARTICLENUM );
		return;
		}
	    currentArtNum = artNum;
	    sendAhbs( article, artNum, which );
	    }
	}

    private void cmdAhbsId( String messageId, char which ) throws NewsDbException, NnrpdException
	{
	NewsDbArticle article = getArticle( messageId );
	if ( article == null )
	    {
	    response( NnrpdUtils.RES_NOSUCHARTICLE );
	    return;
	    }
	sendAhbs( article, -1, which );
	}

    private void sendAhbs( NewsDbArticle article, int artNum, char which ) throws NewsDbException, NnrpdException
	{
	artLog();
	response(
	    whichStatus( which ) + " " + artNum + " " +
	    article.getHeader( "Message-ID" ) + whichStr( which ) );
	switch ( which )
	    {
	    case 'a':
	    pout.print( article.getText() );
	    break;
	    case 'h':
	    pout.print(
		article.getText().substring( 0, article.getHeadLen() ) );
	    break;
	    case 'b':
	    pout.print( article.getText().substring( article.getBodyStart() ) );
	    break;
	    case 's':
	    return;
	    }
	pout.println( "." );
	}

    private static int whichStatus( char which )
	{
	switch ( which )
	    {
	    case 'a': return 220;
	    case 'h': return 221;
	    case 'b': return 222;
	    case 's': return 223;
	    }
	return 500;
	}

    private static String whichStr( char which )
	{
	switch ( which )
	    {
	    case 'a': return " head and body follow";
	    case 'h': return " head follows";
	    case 'b': return " body follows";
	    case 's': return " request text separately";
	    }
	return "???";
	}


    private void sendGroup( NewsDbGroup group )
	{
	pout.println(
	    group.getName() + " " + group.getLastArtNum() + " " +
	    group.getFirstArtNum() + " " + group.getFlag() );
	}
    

    /// Send a response line.
    private void response( String resp ) throws NnrpdException
	{
	debug( clientHost + " > " + resp );
	pout.println( resp );
	}


    private NewsDbArticle getArticle( NewsDbGroup group, int artNum ) throws NewsDbException
	{
	NewsDbArticle article = articleCache.getArticle( group, artNum );
	if ( article == null )
	    {
	    article = newsDb.getArticle( group, artNum );
	    if ( article != null )
		articleCache.addArticle( article, group, artNum );
	    }
	return article;
	}

    private NewsDbArticle getArticle( String messageId ) throws NewsDbException
	{
	NewsDbArticle article = articleCache.getArticle( messageId );
	if ( article == null )
	    {
	    article = newsDb.getArticle( messageId );
	    if ( article != null )
		articleCache.addArticle( article, messageId );
	    }
	return article;
	}
    

    /// Parse a range spec for the XHDR and XOVER commands.
    private int[] parseRange( String rangeStr )
	{
	try
	    {
	    int[] range = new int[2];
	    int dash = rangeStr.indexOf( '-' );
	    if ( dash == -1 )
		{
		range[0] = range[1] = Integer.parseInt( rangeStr );
		}
	    else
		{
		String firstStr = rangeStr.substring( 0, dash );
		String lastStr = rangeStr.substring( dash + 1 );
		if ( firstStr.length() == 0 )
		    range[0] = currentGroup.getFirstArtNum();
		else
		    range[0] = Integer.parseInt( firstStr );
		if ( lastStr.length() == 0 )
		    range[1] = currentGroup.getLastArtNum();
		else
		    range[1] = Integer.parseInt( lastStr );
		}
	    return range;
	    }
	catch ( NumberFormatException e )
	    {
	    return null;
	    }
	}
    

    /// Log an article transfer.
    private void artLog() throws NnrpdException
	{
	++artCount;
	++groupArts;
	}

    /// Log group stats.  Call just before you change groups, or exit.
    private void groupLog() throws NnrpdException
	{
	if ( currentGroup != null )
	    {
	    notice(
		clientHost + " group " + currentGroup.getName() +
		" " + groupArts );
	    ++groupCount;
	    }
	groupArts = 0;
	}
    
    /// Log session stats.  Call upon exit.
    private void sessionLog() throws NnrpdException
	{
	long now = System.currentTimeMillis();
	groupLog();
	notice(
	    clientHost + " exit articles " + artCount +
	    " groups " + groupCount );
	if ( postsOk != 0 || postsBad != 0 )
	    notice(
		clientHost + " posts received " + postsOk +
		" rejected " + postsBad );
	notice( clientHost + " elapsed " + ( now - startTime ) / 1000 );
	}


    private void debug( String message ) throws NnrpdException
	{
	nnrpd.debug( message );
	}

    private void info( String message ) throws NnrpdException
	{
	nnrpd.info( message );
	}

    private void notice( String message ) throws NnrpdException
	{
	nnrpd.notice( message );
	}

    private void warning( String message ) throws NnrpdException
	{
	nnrpd.warning( message );
	}

    private void error( String message ) throws NnrpdException
	{
	nnrpd.error( message );
	}

    private void crit( String message ) throws NnrpdException
	{
	nnrpd.crit( message );
	}

    private void alert( String message ) throws NnrpdException
	{
	nnrpd.alert( message );
	}

    private void emerg( String message ) throws NnrpdException
	{
	nnrpd.emerg( message );
	}

    }