commons-net.jar is the bytecode of Apache Commons Net library, which implements the client side of many basic Internet protocols.

Apache Commons Net Source Code files are provided in the binary packge (commons-net-3.8.0-bin.zip). You can download it at Apache Commons Net Website.

The source code of commons-net-3.8.0.jar is provided below:

⏎ org/apache/commons/net/telnet/TelnetOutputStream.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.IOException;
import java.io.OutputStream;

/**
 * Wraps an output stream.
 * <p>
 * In binary mode, the only conversion is to double IAC.
 * <p>
 * In ASCII mode, if convertCRtoCRLF is true (currently always true), any CR is converted to CRLF.
 * IACs are doubled.
 * Also a bare LF is converted to CRLF and a bare CR is converted to CR\0
 * <p>
 */


final class TelnetOutputStream extends OutputStream
{
    private final TelnetClient client;
    // TODO there does not appear to be any way to change this value - should it be a ctor parameter?
    private final boolean convertCRtoCRLF = true;
    private boolean lastWasCR;

    TelnetOutputStream(final TelnetClient client)
    {
        this.client = client;
    }


    /**
     * Writes a byte to the stream.
     * <p>
     * @param ch The byte to write.
     * @throws IOException If an error occurs while writing to the underlying
     *            stream.
     */
    @Override
    public void write(int ch) throws IOException
    {

        synchronized (client)
        {
            ch &= 0xff;

            if (client.requestedWont(TelnetOption.BINARY)) // i.e. ASCII
            {
                if (lastWasCR)
                {
                    if (convertCRtoCRLF)
                    {
                        client.sendByte('\n');
                        if (ch == '\n') // i.e. was CRLF anyway
                        {
                            lastWasCR = false;
                            return ;
                        }
                    } // __convertCRtoCRLF
                    else if (ch != '\n')
                     {
                        client.sendByte('\0'); // RFC854 requires CR NUL for bare CR
                    }
                }

                switch (ch)
                {
                case '\r':
                    client.sendByte('\r');
                    lastWasCR = true;
                    break;
                case '\n':
                    if (!lastWasCR) { // convert LF to CRLF
                        client.sendByte('\r');
                    }
                    client.sendByte(ch);
                    lastWasCR = false;
                    break;
                case TelnetCommand.IAC:
                    client.sendByte(TelnetCommand.IAC);
                    client.sendByte(TelnetCommand.IAC);
                    lastWasCR = false;
                    break;
                default:
                    client.sendByte(ch);
                    lastWasCR = false;
                    break;
                }
            } // end ASCII
            else if (ch == TelnetCommand.IAC)
            {
                client.sendByte(ch);
                client.sendByte(TelnetCommand.IAC);
            } else {
                client.sendByte(ch);
            }
        }
    }


    /**
     * Writes a byte array to the stream.
     * <p>
     * @param buffer  The byte array to write.
     * @throws IOException If an error occurs while writing to the underlying
     *            stream.
     */
    @Override
    public void write(final byte buffer[]) throws IOException
    {
        write(buffer, 0, buffer.length);
    }


    /**
     * Writes a number of bytes from a byte array to the stream starting from
     * a given offset.
     * <p>
     * @param buffer  The byte array to write.
     * @param offset  The offset into the array at which to start copying data.
     * @param length  The number of bytes to write.
     * @throws IOException If an error occurs while writing to the underlying
     *            stream.
     */
    @Override
    public void write(final byte buffer[], int offset, int length) throws IOException
    {
        synchronized (client)
        {
            while (length-- > 0) {
                write(buffer[offset++]);
            }
        }
    }

    /** Flushes the stream. */
    @Override
    public void flush() throws IOException
    {
        client.flushOutputStream();
    }

    /** Closes the stream. */
    @Override
    public void close() throws IOException
    {
        client.closeOutputStream();
    }
}

⏎ org/apache/commons/net/telnet/TelnetOutputStream.java

Or download all of them as a single archive file:

File name: commons-net-3.8.0-sources.jar
File size: 437325 bytes
Release date: 2020-01-22
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