com.khubla.telnet.TelnetServer Maven / Gradle / Ivy

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/*
 * Copyright (C) khubla.com - All Rights Reserved
 * Unauthorized copying of this file, via any medium is strictly prohibited
 * Proprietary and confidential
 * Written by Tom Everett , 2018
 */
package com.khubla.telnet;

import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.khubla.telnet.nvt.AuthenticationHandler;
import com.khubla.telnet.nvt.NVT;
import com.khubla.telnet.shell.Shell;
import com.khubla.telnet.shell.ShellFactory;

public class TelnetServer implements Runnable {
   /**
    * logger
    */
   private static final Logger logger = LoggerFactory.getLogger(TelnetServer.class);
   /**
    * thread pool size
    */
   private final int threads;
   /**
    * port
    */
   private final int port;
   /**
    * Shell Factory
    */
   private final ShellFactory shellFactory;
   /**
    * run flag
    */
   private final AtomicBoolean running = new AtomicBoolean(true);
   /**
    * auth handler
    */
   private final AuthenticationHandler authenticationHandler;

   public TelnetServer(int port, int threads, ShellFactory shellFactory, AuthenticationHandler authenticationHandler) {
      this.authenticationHandler = authenticationHandler;
      this.port = port;
      this.threads = threads;
      this.shellFactory = shellFactory;
   }

   @Override
   public void run() {
      ServerSocket serverSocket = null;
      try {
         /*
          * thread pool
          */
         final ExecutorService executorService = new ThreadPoolExecutor(threads, threads, 1, TimeUnit.MINUTES, new ArrayBlockingQueue(threads, true),
               new ThreadPoolExecutor.CallerRunsPolicy());
         /*
          * listener
          */
         serverSocket = new ServerSocket(port);
         Socket clientSocket = null;
         System.out.println("Telnet server listening on port: " + port);
         while (running.get()) {
            try {
               /*
                * accept connection
                */
               clientSocket = serverSocket.accept();
               /*
                * show
                */
               logger.info("Accepted connection from: " + clientSocket.getInetAddress().toString());
               /*
                * create shell
                */
               final Shell shell = shellFactory.createShell(new NVT(clientSocket, authenticationHandler));
               /*
                * submit to pool
                */
               executorService.submit(shell);
            } catch (final Exception e) {
               clientSocket.close();
               logger.error(e.getMessage(), e);
            }
         }
      } catch (final Exception e) {
         logger.error(e.getMessage(), e);
      } finally {
         if (null != serverSocket) {
            try {
               serverSocket.close();
            } catch (final Exception e) {
               logger.error(e.getMessage(), e);
            }
            serverSocket = null;
         }
      }
   }

   public void shutdown() {
      running.set(false);
   }

   public void start() {
      final Thread thread = new Thread(this);
      thread.start();
   }
}