/** * Jexer - Java Text User Interface * * License: LGPLv3 or later * * This module is licensed under the GNU Lesser General Public License * Version 3. Please see the file "COPYING" in this directory for more * information about the GNU Lesser General Public License Version 3. * * Copyright (C) 2015 Kevin Lamonte * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 3 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this program; if not, see * http://www.gnu.org/licenses/, or write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA * * @author Kevin Lamonte [kevin.lamonte@gmail.com] * @version 1 */ package jexer.net; import java.io.OutputStream; import java.io.IOException; /** * TelnetOutputStream works with TelnetSocket to perform the telnet protocol. */ public final class TelnetOutputStream extends OutputStream { /** * The root TelnetSocket that has my telnet protocol state. */ private TelnetSocket master; /** * The raw socket's OutputStream. */ private OutputStream output; /** * Package private constructor. * * @param master the master TelnetSocket * @param output the underlying socket's OutputStream */ TelnetOutputStream(final TelnetSocket master, final OutputStream output) { this.master = master; this.output = output; } // OutputStream interface ------------------------------------------------- /** * Closes this output stream and releases any system resources associated * with this stream. * * @throws IOException if an I/O error occurs */ @Override public void close() throws IOException { if (output != null) { output.close(); output = null; } } /** * Flushes this output stream and forces any buffered output bytes to be * written out. * * @throws IOException if an I/O error occurs */ @Override public void flush() throws IOException { if ((master.binaryMode == false) && (writeCR == true)) { // The last byte sent to this.write() was a CR, which was never // actually sent. So send the CR in ascii mode, then flush. // CR -> CR NULL output.write(master.C_CR); output.write(master.C_NUL); writeCR = false; } output.flush(); } /** * Writes b.length bytes from the specified byte array to this output * stream. * * @param b the data. * @throws IOException if an I/O error occurs */ @Override public void write(final byte[] b) throws IOException { writeImpl(b, 0, b.length); } /** * Writes len bytes from the specified byte array starting at offset off * to this output stream. * * @param b the data. * @param off the start offset in the data. * @param len the number of bytes to write. * @throws IOException if an I/O error occurs */ @Override public void write(final byte[] b, final int off, final int len) throws IOException { writeImpl(b, off, len); } /** * Writes the specified byte to this output stream. * * @param b the byte to write. * @throws IOException if an I/O error occurs */ @Override public void write(final int b) throws IOException { byte [] bytes = new byte[1]; bytes[0] = (byte)b; writeImpl(bytes, 0, 1); } /** * Writes b.length bytes from the specified byte array to this output * stream. Note package private access. * * @param b the data. * @throws IOException if an I/O error occurs */ void rawWrite(final byte[] b) throws IOException { output.write(b, 0, b.length); } // Telnet protocol -------------------------------------------------------- /** * When true, the last byte the caller passed to write() was a CR. */ private boolean writeCR = false; /** * Writes len bytes from the specified byte array starting at offset off * to this output stream. * * @param b the data. * @param off the start offset in the data. * @param len the number of bytes to write. * @throws IOException if an I/O error occurs */ private void writeImpl(final byte[] b, final int off, final int len) throws IOException { byte [] writeBuffer = new byte[Math.max(len, 4)]; int writeBufferI = 0; for (int i = 0; i < len; i++) { if (writeBufferI >= writeBuffer.length - 4) { // Flush what we have generated so far and reset the buffer, // because the next byte could generate up to 4 output bytes // (CR ). output.write(writeBuffer, 0, writeBufferI); writeBufferI = 0; } // Pull the next byte byte ch = b[i + off]; if (master.binaryMode == true) { if (ch == master.TELNET_IAC) { // IAC -> IAC IAC writeBuffer[writeBufferI++] = (byte)master.TELNET_IAC; writeBuffer[writeBufferI++] = (byte)master.TELNET_IAC; } else { // Anything else -> just send writeBuffer[writeBufferI++] = ch; } continue; } // Non-binary mode: more complicated. We use writeCR to handle // the case that the last byte of b was a CR. // Bare carriage return -> CR NUL if (ch == master.C_CR) { if (writeCR == true) { // Flush the previous CR to the stream. // CR -> CR NULL writeBuffer[writeBufferI++] = (byte)master.C_CR; writeBuffer[writeBufferI++] = (byte)master.C_NUL; } writeCR = true; } else if (ch == master.C_LF) { if (writeCR == true) { // CR LF -> CR LF writeBuffer[writeBufferI++] = (byte)master.C_CR; writeBuffer[writeBufferI++] = (byte)master.C_LF; writeCR = false; } else { // Bare LF -> LF writeBuffer[writeBufferI++] = ch; } } else if (ch == master.TELNET_IAC) { if (writeCR == true) { // CR -> CR NULL writeBuffer[writeBufferI++] = (byte)master.C_CR; writeBuffer[writeBufferI++] = (byte)master.C_NUL; writeCR = false; } // IAC -> IAC IAC writeBuffer[writeBufferI++] = (byte)master.TELNET_IAC; writeBuffer[writeBufferI++] = (byte)master.TELNET_IAC; } else { if (writeCR == true) { // CR -> CR NULL writeBuffer[writeBufferI++] = (byte)master.C_CR; writeBuffer[writeBufferI++] = (byte)master.C_NUL; writeCR = false; } else { // Normal character */ writeBuffer[writeBufferI++] = ch; } } } // while (i < userbuf.length) if (writeBufferI > 0) { // Flush what we have generated so far and reset the buffer. output.write(writeBuffer, 0, writeBufferI); } } }