telnetinputstream.java

来自「apache推出的net包」· Java 代码 · 共 602 行 · 第 1/2 页

/*
 * Copyright 2003-2004 The Apache Software Foundation
 *
 * 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.commons.net.telnet;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;

/***
 *
 * <p>
 *
 * <p>
 * <p>
 * @author Daniel F. Savarese
 * @author Bruno D'Avanzo
 ***/


final class TelnetInputStream extends BufferedInputStream implements Runnable
{
    static final int _STATE_DATA = 0, _STATE_IAC = 1, _STATE_WILL = 2,
                     _STATE_WONT = 3, _STATE_DO = 4, _STATE_DONT = 5,
                     _STATE_SB = 6, _STATE_SE = 7, _STATE_CR = 8, _STATE_IAC_SB = 9;

    private boolean __hasReachedEOF, __isClosed;
    private boolean __readIsWaiting;
    private int __receiveState, __queueHead, __queueTail, __bytesAvailable;
    private int[] __queue;
    private TelnetClient __client;
    private Thread __thread;
    private IOException __ioException;

    /* TERMINAL-TYPE option (start)*/
    private int __suboption[] = new int[256];
    private int __suboption_count = 0;
    /* TERMINAL-TYPE option (end)*/

    private boolean __threaded;

    TelnetInputStream(InputStream input, TelnetClient client,
                      boolean readerThread)
    {
        super(input);
        __client = client;
        __receiveState = _STATE_DATA;
        __isClosed = true;
        __hasReachedEOF = false;
        // Make it 2049, because when full, one slot will go unused, and we
        // want a 2048 byte buffer just to have a round number (base 2 that is)
        __queue = new int[2049];
        __queueHead = 0;
        __queueTail = 0;
        __bytesAvailable = 0;
        __ioException = null;
        __readIsWaiting = false;
        __threaded = false;
        if(readerThread)
            __thread = new Thread(this);
        else
            __thread = null;
    }

    TelnetInputStream(InputStream input, TelnetClient client) {
        this(input, client, true);
    }

    void _start()
    {
        if(__thread == null)
            return;

        int priority;
        __isClosed = false;
        // Need to set a higher priority in case JVM does not use pre-emptive
        // threads.  This should prevent scheduler induced deadlock (rather than
        // deadlock caused by a bug in this code).
        priority = Thread.currentThread().getPriority() + 1;
        if (priority > Thread.MAX_PRIORITY)
            priority = Thread.MAX_PRIORITY;
        __thread.setPriority(priority);
        __thread.setDaemon(true);
        __thread.start();
        __threaded = true;
    }


    // synchronized(__client) critical sections are to protect against
    // TelnetOutputStream writing through the telnet client at same time
    // as a processDo/Will/etc. command invoked from TelnetInputStream
    // tries to write.
    private int __read() throws IOException
    {
        int ch;

_loop:
        while (true)
        {
            // Exit only when we reach end of stream.
            if ((ch = super.read()) < 0)
                return -1;

            ch = (ch & 0xff);

            /* Code Section added for supporting AYT (start)*/
            synchronized (__client)
            {
                __client._processAYTResponse();
            }
            /* Code Section added for supporting AYT (end)*/

            /* Code Section added for supporting spystreams (start)*/
            __client._spyRead(ch);
            /* Code Section added for supporting spystreams (end)*/

_mainSwitch:
            switch (__receiveState)
            {

            case _STATE_CR:
                if (ch == '\0')
                {
                    // Strip null
                    continue;
                }
                // How do we handle newline after cr?
                //  else if (ch == '\n' && _requestedDont(TelnetOption.ECHO) &&

                // Handle as normal data by falling through to _STATE_DATA case

            case _STATE_DATA:
                if (ch == TelnetCommand.IAC)
                {
                    __receiveState = _STATE_IAC;
                    continue;
                }


                if (ch == '\r')
                {
                    synchronized (__client)
                    {
                        if (__client._requestedDont(TelnetOption.BINARY))
                            __receiveState = _STATE_CR;
                        else
                            __receiveState = _STATE_DATA;
                    }
                }
                else
                    __receiveState = _STATE_DATA;
                break;

            case _STATE_IAC:
                switch (ch)
                {
                case TelnetCommand.WILL:
                    __receiveState = _STATE_WILL;
                    continue;
                case TelnetCommand.WONT:
                    __receiveState = _STATE_WONT;
                    continue;
                case TelnetCommand.DO:
                    __receiveState = _STATE_DO;
                    continue;
                case TelnetCommand.DONT:
                    __receiveState = _STATE_DONT;
                    continue;
                /* TERMINAL-TYPE option (start)*/
                case TelnetCommand.SB:
                    __suboption_count = 0;
                    __receiveState = _STATE_SB;
                    continue;
                /* TERMINAL-TYPE option (end)*/
                case TelnetCommand.IAC:
                    __receiveState = _STATE_DATA;
                    break;
                default:
                    break;
                }
                __receiveState = _STATE_DATA;
                continue;
            case _STATE_WILL:
                synchronized (__client)
                {
                    __client._processWill(ch);
                    __client._flushOutputStream();
                }
                __receiveState = _STATE_DATA;
                continue;
            case _STATE_WONT:
                synchronized (__client)
                {
                    __client._processWont(ch);
                    __client._flushOutputStream();
                }
                __receiveState = _STATE_DATA;
                continue;
            case _STATE_DO:
                synchronized (__client)
                {
                    __client._processDo(ch);
                    __client._flushOutputStream();
                }
                __receiveState = _STATE_DATA;
                continue;
            case _STATE_DONT:
                synchronized (__client)
                {
                    __client._processDont(ch);
                    __client._flushOutputStream();
                }
                __receiveState = _STATE_DATA;
                continue;
            /* TERMINAL-TYPE option (start)*/
            case _STATE_SB:
                switch (ch)
                {
                case TelnetCommand.IAC:
                    __receiveState = _STATE_IAC_SB;
                    continue;
                default:
                    // store suboption char
                    __suboption[__suboption_count++] = ch;
                    break;
                }
                __receiveState = _STATE_SB;
                continue;
            case _STATE_IAC_SB:
                switch (ch)
                {
                case TelnetCommand.SE:
                    synchronized (__client)
                    {
                        __client._processSuboption(__suboption, __suboption_count);
                        __client._flushOutputStream();
                    }
                    __receiveState = _STATE_DATA;
                    continue;
                default:
                    __receiveState = _STATE_SB;
                    break;
                }
                __receiveState = _STATE_DATA;
                continue;
            /* TERMINAL-TYPE option (end)*/
            }

            break;
        }

        return ch;
    }

    // synchronized(__client) critical sections are to protect against
    // TelnetOutputStream writing through the telnet client at same time
    // as a processDo/Will/etc. command invoked from TelnetInputStream
    // tries to write.
    private void __processChar(int ch) throws InterruptedException
    {
        // Critical section because we're altering __bytesAvailable,
        // __queueTail, and the contents of _queue.
        synchronized (__queue)
        {
            while (__bytesAvailable >= __queue.length - 1)
            {
                if(__threaded)
                {
                    __queue.notify();
                    try
                    {
                        __queue.wait();
                    }
                    catch (InterruptedException e)
                    {
                        throw e;
                    }
                }
            }

            // Need to do this in case we're not full, but block on a read
            if (__readIsWaiting && __threaded)
            {
                __queue.notify();
            }

            __queue[__queueTail] = ch;
            ++__bytesAvailable;