| /* |
| * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package sun.net; |
| |
| import java.io.*; |
| |
| /** |
| * This class provides input and output streams for telnet clients. |
| * This class overrides write to do CRLF processing as specified in |
| * RFC 854. The class assumes it is running on a system where lines |
| * are terminated with a single newline {@literal <LF>} character. |
| * |
| * This is the relevant section of RFC 824 regarding CRLF processing: |
| * |
| * <pre> |
| * The sequence "CR LF", as defined, will cause the NVT to be |
| * positioned at the left margin of the next print line (as would, |
| * for example, the sequence "LF CR"). However, many systems and |
| * terminals do not treat CR and LF independently, and will have to |
| * go to some effort to simulate their effect. (For example, some |
| * terminals do not have a CR independent of the LF, but on such |
| * terminals it may be possible to simulate a CR by backspacing.) |
| * Therefore, the sequence "CR LF" must be treated as a single "new |
| * line" character and used whenever their combined action is |
| * intended; the sequence "CR NUL" must be used where a carriage |
| * return alone is actually desired; and the CR character must be |
| * avoided in other contexts. This rule gives assurance to systems |
| * which must decide whether to perform a "new line" function or a |
| * multiple-backspace that the TELNET stream contains a character |
| * following a CR that will allow a rational decision. |
| * |
| * Note that "CR LF" or "CR NUL" is required in both directions |
| * (in the default ASCII mode), to preserve the symmetry of the |
| * NVT model. Even though it may be known in some situations |
| * (e.g., with remote echo and suppress go ahead options in |
| * effect) that characters are not being sent to an actual |
| * printer, nonetheless, for the sake of consistency, the protocol |
| * requires that a NUL be inserted following a CR not followed by |
| * a LF in the data stream. The converse of this is that a NUL |
| * received in the data stream after a CR (in the absence of |
| * options negotiations which explicitly specify otherwise) should |
| * be stripped out prior to applying the NVT to local character |
| * set mapping. |
| * </pre> |
| * |
| * @author Jonathan Payne |
| */ |
| |
| public class TelnetOutputStream extends BufferedOutputStream { |
| boolean stickyCRLF = false; |
| boolean seenCR = false; |
| |
| public boolean binaryMode = false; |
| |
| public TelnetOutputStream(OutputStream fd, boolean binary) { |
| super(fd); |
| binaryMode = binary; |
| } |
| |
| /** |
| * set the stickyCRLF flag. Tells whether the terminal considers CRLF as a single |
| * char. |
| * |
| * @param on the <code>boolean</code> to set the flag to. |
| */ |
| public void setStickyCRLF(boolean on) { |
| stickyCRLF = on; |
| } |
| |
| /** |
| * Writes the int to the stream and does CR LF processing if necessary. |
| */ |
| public void write(int c) throws IOException { |
| if (binaryMode) { |
| super.write(c); |
| return; |
| } |
| |
| if (seenCR) { |
| if (c != '\n') |
| super.write(0); |
| super.write(c); |
| if (c != '\r') |
| seenCR = false; |
| } else { // !seenCR |
| if (c == '\n') { |
| super.write('\r'); |
| super.write('\n'); |
| return; |
| } |
| if (c == '\r') { |
| if (stickyCRLF) |
| seenCR = true; |
| else { |
| super.write('\r'); |
| c = 0; |
| } |
| } |
| super.write(c); |
| } |
| } |
| |
| /** |
| * Write the bytes at offset <i>off</i> in buffer <i>bytes</i> for |
| * <i>length</i> bytes. |
| */ |
| public void write(byte bytes[], int off, int length) throws IOException { |
| if (binaryMode) { |
| super.write(bytes, off, length); |
| return; |
| } |
| |
| while (--length >= 0) { |
| write(bytes[off++]); |
| } |
| } |
| } |