/*The following code is instructive if you're learning how to do networking
/*and threads in Java. It defines the ServerThread class.

/****************************************************************************/
/*                                                                          */
/* Copyright (c) 1995-1997 The Fractal Images Company. All Rights Reserved.

/* File name: ServerThread.java                                             */
/*                                                                          */
/* Author: Robert Uomini                                                    */
/****************************************************************************/
import java.util.*;
import java.io.*;
import java.net.*;

public final class ServerThread extends Thread
  {
  Socket        inbound;

  DataInputStream       istream = null;

  BufferedOutputStream  ostream = null;

  String        str = null;
  String        reply = null;
  String        group_name = null;
  String        host_name;
  String        subscribed_groups = "";
  String        unsubscribed_groups = "";
  String        article_num = null;
  String        welcome_msg;
  String        command;
  String        offline_dir = "offline_articles";
  String        cache_dir = "post_queue";

  InetAddress   local_addr = null;
  InetAddress   inet_addr;

  byte          byte_array[];

  int           index;

  boolean       done;

  public ServerThread(Socket inbound)
    {
    this.inbound = inbound;
    }

/****************************************************************************/
/*  A ServerThread class is instantiated by OfflineServer, whenever         */
/*  WebReader goes offline or is started in offline mode. First, certain    */
/*  stream classes are created for handling requests from, and responses    */
/*  to, the client. The local host IP address is also fetched. If the IP    */
/*  address of the host issuing the client request, the request is junked   */
/*  and the connection is terminated.                                       */
/****************************************************************************/
  public void run()
    {
    String      group_names;

    try
      {
      istream = new DataInputStream(inbound.getInputStream());
      ostream = new BufferedOutputStream(inbound.getOutputStream());
      }
    catch (IOException e)
      {
      System.out.println("Error opening stream: " + e);
      System.exit(0);
      }
    try
      {
      local_addr = InetAddress.getLocalHost();
      }
    catch (UnknownHostException e){}
    inet_addr = inbound.getInetAddress();
    if (local_addr.toString().indexOf(inet_addr.toString()) != -1 ||
        inet_addr.toString().equals("127.0.0.1"))
      {
      welcome_msg = "200 " + local_addr;
      done = false;
      }
    else
      {
      welcome_msg = "502 NNTP server can't talk to you.  Goodbye.";
      done = true;
      }
    welcome_msg += "\n";
    byte_array = new byte[welcome_msg.length()];
/****************************************************************************/
/*  Send the reply to the client's open request. Stay in the loop, reading  */
/*  and processing client requests until either a null request or a Quit    */
/*  command is received.                                                    */
/****************************************************************************/
    welcome_msg.getBytes(0, welcome_msg.length(), byte_array, 0);
    try
      {
      ostream.write(byte_array);
      ostream.flush();
      }
    catch (IOException e){}
    while(!done)
      {
      try
        {
        str = istream.readLine();
        }
      catch (IOException e){}
      if (str == null || str.trim().toUpperCase().equals("QUIT"))
        {
        done = true;
        }
      else
        {
/****************************************************************************/
/*  Process each of the valid NNTP server command strings in turn.          */
/****************************************************************************/
        command = str.toUpperCase();
        if (command.startsWith("ARTICLE "))
          {
          article_num = str.substring("ARTICLE ".length());
          reply = get_article(group_name, article_num, 220);
          }
        if (command.startsWith("AUTHINFO "))
          {
          reply = "281 Authentication accepted";
          }
        if (command.startsWith("GROUP "))
          {
          group_name = str.substring("GROUP ".length());
          reply = get_group_header(group_name);
          }
        if (command.startsWith("HEAD "))
          {
          article_num = str.substring("HEAD ".length());
          reply = get_article(group_name, article_num, 221);
          if ((index = reply.indexOf("\n\n")) != -1)
                reply = reply.substring(0, index);
          reply += "\n.";
          }
        if (command.startsWith("HELP"))
          {
          reply = "100 Legal commands\n" + "  article number\n" +
                "  authinfo user name\n" + "  group newsgroup\n" +
                "  head number\n" + "  help\n" + "  list\n" +
                "  mode reader\n" + "  newgroups yymmdd hhmmss\n" +
                "  post\n" + "  xover number\n.";
          }
        if (command.equals("LIST"))
          {
          subscribed_groups = list_groups("Newsrc.subscribed", host_name);
          unsubscribed_groups = list_groups("Newsrc.unsubscribed", host_name);
          reply = "215 list of newsgroups follows" + "\n" +
                subscribed_groups + unsubscribed_groups + ".";
          }
        if (command.startsWith("LIST NEWSGROUPS "))
          {
          reply = get_desc(str.substring("LIST NEWSGROUPS ".length()),
                host_name);
          }
        if (command.startsWith("MODE READER"))
          {
          reply = "200 Hello, you can post";
          }
        if (command.startsWith("NEWGROUPS "))
          {
          reply = "231 New newsgroups follow.\n.";
          }
        if (command.startsWith("POST"))
          {
          reply = "340 Ok";
          reply += "\n";
          byte_array = new byte[reply.length()];
          reply.getBytes(0, reply.length(), byte_array, 0);
          try
            {
            ostream.write(byte_array);
            ostream.flush();
            }
          catch (IOException e){}
          reply = "";
          do
            {
            try
              {
              str = istream.readLine();
              }
            catch (IOException e)
              {
              reply = "441 posting failed";
              continue;
              }
            if (str != null) reply += str + "\n";
            }
          while(!str.equals("."));
          index = reply.indexOf(WRLiterals.NEWSGPS_HDR) +
                WRLiterals.NEWSGPS_HDR.length();
          group_names = reply.substring(index);
          group_names = group_names.substring(0, group_names.indexOf("\n"));
          if (group_names.length() == 0)
            {
            reply = "441 Required \"Newsgroups\" header is missing";
            }
          else
            {
            reply = reply.substring(0, reply.lastIndexOf(".")).trim();
            reply = save_article(cache_dir, group_names, reply);
            }
          }
        if (command.startsWith("SET HOSTNAME "))
          {
          host_name = str.substring("SET HOSTNAME ".length());
          if (host_name != null)
            {
            cache_dir += "." + host_name;
            offline_dir += "." + host_name;
            }
          reply = "200 File names set";
          }
        if (command.startsWith("XOVER "))
          {
          article_num = str.substring("XOVER ".length());
          reply = get_header(group_name, article_num);
          }
        if (command.length() < 3)
          {
          reply = command;
          }
        if (!command.startsWith("ARTICLE ") &&
            !command.startsWith("AUTHINFO ") &&
            !command.startsWith("GROUP ") &&
            !command.startsWith("HEAD ") &&
            !command.startsWith("HELP") &&
            !command.equals("LIST") &&
            !command.startsWith("LIST NEWSGROUPS ") &&
            !command.startsWith("MODE READER") &&
            !command.startsWith("NEWGROUPS ") &&
            !command.startsWith("POST") &&
            !command.startsWith("SET HOSTNAME") &&
            !command.startsWith("XOVER "))
          {
          reply = "500 command not recognized";
          }
        reply += "\n";
        byte_array = new byte[reply.length()];
        reply.getBytes(0, reply.length(), byte_array, 0);
        try
          {
          ostream.write(byte_array);
          ostream.flush();
          }
        catch (IOException e){}
        }
      str = null;
      }
    try
      {
      inbound.close();
      }
    catch (IOException e){}
    }

/****************************************************************************/
/*
/****************************************************************************/
/*  The list_groups() method processes the LIST command.                    */
/****************************************************************************/
  public String list_groups(String file_name, String host_name)
    {
    RandomAccessFile    groups_file;

    String              tmp = "";

    StringBuffer        groups;

    int                 index;

    if (host_name.length() > 0) file_name += "." + host_name;
    try
      {
      groups_file = new RandomAccessFile(file_name, "r");
      }
    catch (IOException e)
      {
      return "";
      }
    try
      {
      tmp = groups_file.readLine();
      }
    catch (IOException e)
      {
      return "";
      }
    groups = new StringBuffer();
    for(; tmp != null;)
      {
      try
        {
        tmp = groups_file.readLine();
        }
      catch (IOException e)
        {
        return "";
        }
      if (tmp != null)
        {
        if ((index = tmp.indexOf(WRLiterals.COLON)) != -1 ||
            (index = tmp.indexOf(WRLiterals.EXCLAM)) != -1)
          {
          groups.append(tmp.substring(0, index) + "\n");
          }
        }
      }
    return groups.toString();
    }

/****************************************************************************/
/*  The get_group_header() method processes the GROUP command.              */
/****************************************************************************/
  public String get_group_header(String group)
    {
    File                tmp_file;

    RandomAccessFile    save_file = null;

    String              tmp_name;
    String              header = null;

    tmp_file = new File(offline_dir);
    tmp_name = tmp_file.getAbsolutePath() + tmp_file.separator + group;
    try
      {
      save_file = new RandomAccessFile(tmp_name, "r");
      }
    catch (IOException e)
      {
      return "411";
      }
    try
      {
      header = save_file.readLine();
      }
    catch (IOException e)
      {
      return "411";
      }
    return header;
    }

/****************************************************************************/
/*  The get_header() method processes the XOVER command.                    */
/****************************************************************************/
  public String get_header(String group, String article_num)
    {
    File                tmp_file;

    RandomAccessFile    save_file = null;

    String              tmp_name;
    String              first_article;
    String              last_article;
    String              header = null;
    String              reply;
    String              num_articles;
    String              article = null;

    int                 index;
    int                 first_art;
    int                 last_art;
    int                 art_num;
    int                 num_art;

    if (group == null) return "412";
    tmp_file = new File(offline_dir);
    tmp_name = tmp_file.getAbsolutePath() + tmp_file.separator + group;
    try
      {
      save_file = new RandomAccessFile(tmp_name, "r");
      }
    catch (IOException e)

      {
      return "412";
      }
    try
      {
      header = save_file.readLine();
      }
    catch (IOException e)
      {
      return "420";
      }
    first_article = header.substring(header.indexOf(WRLiterals.BLANK) + 1);
    num_articles =
        first_article.substring(0, first_article.indexOf(WRLiterals.BLANK));
    first_article =
        first_article.substring(first_article.indexOf(WRLiterals.BLANK) + 1);
    last_article =
        first_article.substring(first_article.indexOf(WRLiterals.BLANK) + 1,
        first_article.lastIndexOf(WRLiterals.BLANK));
    first_article =
        first_article.substring(0, first_article.indexOf(WRLiterals.BLANK));
    num_art = Integer.parseInt(num_articles);
    first_art = Integer.parseInt(first_article);
    last_art = Integer.parseInt(last_article);
    art_num = Integer.parseInt(article_num);
    if (art_num < first_art || art_num > last_art) return "420";
    header = get_selected_header(save_file, article_num, num_art);
    if (header == null) return "420";
    reply = "224 data follows" + "\n" + header;
    return reply;
    }

/****************************************************************************/
/*  The get_selected_header() method is called by the get_header() method,  */
/*  and fetches a specific article header.                                  */
/****************************************************************************/
  public String get_selected_header(RandomAccessFile save_file,
        String article_num, int num_art)
    {
    String      curr_artnum;
    String      start_ptr;
    String      end_ptr;
    String      subject;
    String      author;
    String      date;
    String      msg_id;
    String      refs;
    String      lines;
    String      header;
    String      tmp;

    byte        data[];

    long        strt = 0;
    long        end = 0;

    int         index;
    int         index2;
    int         data_len;

    boolean     article_found;

    data = new byte[16 * num_art];
    try
      {
      save_file.read(data);
      }
    catch (IOException e)
      {
      return null;
      }
    tmp = new String(data, 0);
    for(index = 0, article_found = false; !article_found && index < num_art;
        index++)
      {
      curr_artnum = tmp.substring(0, 8).trim();
      if (curr_artnum.equals(article_num))
        {
        start_ptr = tmp.substring(8, 16).trim();
        strt = Long.parseLong(start_ptr);
        if (tmp.length() > 16)
          {
          end_ptr = tmp.substring(24, 32).trim();
          end = Long.parseLong(end_ptr);
          }
        else
          {
          try
            {
            end = save_file.length();
            }
          catch (IOException e)
            {
            return null;
            }
          }
        article_found = true;
        }
      tmp = tmp.substring(16);
      }
    if (!article_found) return null;
    try
      {
      save_file.seek(strt);
      }
    catch (IOException e)
      {
      return null;
      }
    header = "";
    data_len = (int)(end - strt);
    subject = "";
    author = "";
    date = "";
    msg_id = "";
    refs = "";
    lines = "";
    try
      {
      tmp = save_file.readLine();
      }
    catch (IOException e)
      {
      return null;
      }
    for(; tmp.length() > 3;)
      {
      if ((index = tmp.indexOf(WRLiterals.SUBJECT_HDR)) != -1)
        {
        subject = tmp.substring(index + WRLiterals.SUBJECT_HDR.length());
        }
      if ((index = tmp.indexOf(WRLiterals.FROM_HDR)) != -1)
        {
        author = tmp.substring(index + WRLiterals.FROM_HDR.length());
        }
      if ((index = tmp.indexOf(WRLiterals.DATE_HDR)) != -1)
        {
        date = tmp.substring(index + WRLiterals.DATE_HDR.length());
        }
      if ((index = tmp.indexOf(WRLiterals.MSGID_HDR)) != -1)
        {
        msg_id = tmp.substring(index + WRLiterals.MSGID_HDR.length());
        }
      if ((index = tmp.indexOf(WRLiterals.REFERENCES_HDR)) != -1)
        {
        refs = tmp.substring(index + WRLiterals.REFERENCES_HDR.length());
        }
      if ((index = tmp.indexOf(WRLiterals.LINES)) != -1)
        {
        lines = tmp.substring(index + WRLiterals.LINES.length());
        }
      try
        {
        tmp = save_file.readLine();
        }
      catch (IOException e)
        {
        return null;
        }
      }
    header = article_num + "\t" + subject + "\t" + author + "\t" +
        date + "\t" + msg_id + "\t" + refs + "\t" + data_len + "\t" + lines +
        "\t" + "\n.";
    return header;
    }

/****************************************************************************/
/*  The get_article() method processes the ARTICLE command and is also used */
/*  by in processing of the HEAD command.                                   */
/****************************************************************************/
  public String get_article(String group, String article_num, int rc)
    {
    File                tmp_file;

    RandomAccessFile    save_file = null;

    String              tmp_name;
    String              first_article;
    String              last_article;
    String              header = null;
    String              reply;
    String              msg_id;
    String              num_articles;
    String              article = null;

    int                 index;
    int                 first_art;
    int                 last_art;
    int                 art_num;
    int                 num_art;

    if (group == null) return "412";
    tmp_file = new File(offline_dir);
    tmp_name = tmp_file.getAbsolutePath() + tmp_file.separator + group;
    try
      {
      save_file = new RandomAccessFile(tmp_name, "r");
      }
    catch (IOException e)
      {
      return "412";
      }
    try
      {
      header = save_file.readLine();
      }
    catch (IOException e)
      {
      return "430";
      }
    first_article = header.substring(header.indexOf(WRLiterals.BLANK) + 1);
    num_articles =
        first_article.substring(0, first_article.indexOf(WRLiterals.BLANK));
    first_article =
        first_article.substring(first_article.indexOf(WRLiterals.BLANK) + 1);
    last_article =
        first_article.substring(first_article.indexOf(WRLiterals.BLANK) + 1,
        first_article.lastIndexOf(WRLiterals.BLANK));
    first_article =
        first_article.substring(0, first_article.indexOf(WRLiterals.BLANK));
    num_art = Integer.parseInt(num_articles);
    first_art = Integer.parseInt(first_article);
    last_art = Integer.parseInt(last_article);
    art_num = Integer.parseInt(article_num);
    if (art_num < first_art || art_num > last_art) return "423";
    article = get_selected_article(save_file, article_num, num_art);
    if (article == null) return "430";
    article = article.substring(article.indexOf(WRLiterals.BLANK)).trim();
    msg_id = "<0>";
    header = article.substring(0, article.indexOf("\n\n") + 2);
    if ((index = header.indexOf(WRLiterals.MSGID_HDR)) != -1)
      {
      msg_id = header.substring(index + WRLiterals.MSGID_HDR.length());
      msg_id = msg_id.substring(0, msg_id.indexOf("\n"));
      }
    reply = rc + WRLiterals.BLANK + article_num + WRLiterals.BLANK + msg_id +
        "\n" + article + "\n.";
    return reply;
    }

/****************************************************************************/
/*  The get_selected_article() method is called by the get_article() method,*/
/*  and fetches a specific article.                                         */
/****************************************************************************/
  public String get_selected_article(RandomAccessFile save_file,
        String article_num, int num_art)
    {
    String      curr_artnum;
    String      start_ptr;
    String      end_ptr;
    String      tmp;

    byte        data[];

    long        strt = 0;
    long        end = 0;

    int         index;

    boolean     article_found;

    data = new byte[16 * num_art];
    try
      {
      save_file.read(data);
      }
    catch (IOException e)
      {
      return null;
      }
    tmp = new String(data, 0);
    for(index = 0, article_found = false; !article_found && index < num_art;
        index++)
      {
      curr_artnum = tmp.substring(0, 8).trim();
      if (curr_artnum.equals(article_num))
        {
        start_ptr = tmp.substring(8, 16).trim();
        strt = Long.parseLong(start_ptr);
        if (tmp.length() > 16)
          {
          end_ptr = tmp.substring(24, 32).trim();
          end = Long.parseLong(end_ptr);
          }
        else
          {
          try
            {
            end = save_file.length();
            }
          catch (IOException e)
            {
            return null;
            }
          }
        article_found = true;
        }
      tmp = tmp.substring(16);
      }
    if (!article_found) return null;
    try
      {
      save_file.seek(strt);
      }
    catch (IOException e)
      {
      return null;
      }
    data = new byte[(int)(end - strt)];
    try
      {
      save_file.read(data);
      }
    catch (IOException e)
      {
      return null;
      }
    return new String(data, 0);
    }

/****************************************************************************/
/*  The get_desc() method processes the LIST NEWSGROUPS command.            */
/****************************************************************************/
  public String get_desc(String group_name, String host_name)
    {
    String              subgp_file_name = "Newsrc.subscribed";
    String              unsubgp_file_name = "Newsrc.unsubscribed";
    String              subdesc_file_name = "desc.subscribed";
    String              unsubdesc_file_name = "desc.unsubscribed";
    String              file_names[];
    String              desc;

    int                 index;

    if (host_name.length() > 0)
      {
      subgp_file_name += "." + host_name;
      unsubgp_file_name += "." + host_name;
      subdesc_file_name += "." + host_name;
      unsubdesc_file_name += "." + host_name;
      }
    file_names = new String[4];
    file_names[0] = subgp_file_name;
    file_names[1] = subdesc_file_name;
    file_names[2] = unsubgp_file_name;
    file_names[3] = unsubdesc_file_name;
    for(index = 0, desc = null; desc == null && index < file_names.length;
        index += 2)
      {
      desc = fetch_desc(group_name, file_names[index], file_names[index + 1]);
      }
    if (desc == null) return "503 group not found";
    return "215 information follows" + "\n" + desc + "\n.";
    }

/****************************************************************************/
/*  The fetch_desc() method is called by the get_desc() method, and is      */
/*  responsible for actually fetching the group description.                */
/****************************************************************************/
  public String fetch_desc(String group_name, String file_name,
        String desc_name)
    {
    RandomAccessFile    groups_file;

    String              tmp_name;
    String              desc;

    StringBuffer        groups;

    int                 index = 0;
    int                 name_index;
    int                 index2;

    boolean             found;

    try
      {
      groups_file = new RandomAccessFile(file_name, "r");
      }
    catch (IOException e)
      {
      return null;
      }
    try
      {
      desc = groups_file.readLine();
      }
    catch (IOException e)
      {
      return null;
      }
    for(name_index = 0, found = false; !found && desc != null; name_index++)
      {
      try
        {
        desc = groups_file.readLine();
        }
      catch (IOException e)
        {
        return null;
        }
      if (desc != null)
        {
        if ((index = desc.indexOf(WRLiterals.COLON)) == -1)
                index = desc.indexOf(WRLiterals.EXCLAM);
        if (desc.substring(0, index).equals(group_name)) found = true;
        }
      }
    if (desc == null) return null;
    try
      {
      groups_file = new RandomAccessFile(desc_name, "r");
      }
    catch (IOException e)
      {
      return null;
      }
    try
      {
      desc = groups_file.readLine();
      }
    catch (IOException e)
      {
      return null;
      }
    for(index2 = 0; index2 < name_index; index2++)
      {
      try
        {
        desc = groups_file.readLine();
        }
      catch (IOException e)
        {
        return null;
        }
      }
    return desc;
    }

/****************************************************************************/
/*  The save_article() method is used in processing the POST command, and   */
/*  serves to save the article to disk.                                     */
/****************************************************************************/
  public static String save_article(String file_dir, String group_names,
        String article_text)
    {
    File                tmp_file;

    RandomAccessFile    save_file = null;

    String              tmp_name;

    StringTokenizer     st;

    st = new StringTokenizer(group_names, ",");
    while (st.hasMoreTokens())
      {
      tmp_file = new File(file_dir);
      tmp_name = tmp_file.getAbsolutePath() + tmp_file.separator +
        st.nextToken().trim();
      try
        {
        save_file = new RandomAccessFile(tmp_name, "rw");
        }
      catch (IOException e)
        {
        return "441 posting failed";
        }
      try
        {
        save_file.seek(save_file.length());
        save_file.writeBytes(article_text.length() + 1 + "\n");
        save_file.writeBytes(article_text + "\n");
        }
      catch (IOException e)
        {
        return "441 posting failed";
        }
      }
    return "240 article posted ok";
    }
  }