author | chegar |
Fri, 18 Oct 2019 21:25:01 +0100 | |
branch | datagramsocketimpl-branch |
changeset 58697 | e3ff12d14d43 |
parent 47216 | 71c04702a3d5 |
permissions | -rw-r--r-- |
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/* |
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6dadb192ad81
8029235: Update copyright year to match last edit in jdk8 jdk repository for 2013
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changeset
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* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package sun.net; |
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import java.io.*; |
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/** |
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* This class provides input and output streams for telnet clients. |
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* This class overrides write to do CRLF processing as specified in |
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* RFC 854. The class assumes it is running on a system where lines |
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* are terminated with a single newline {@literal <LF>} character. |
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* |
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* This is the relevant section of RFC 824 regarding CRLF processing: |
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* |
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* <pre> |
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* The sequence "CR LF", as defined, will cause the NVT to be |
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* positioned at the left margin of the next print line (as would, |
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* for example, the sequence "LF CR"). However, many systems and |
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* terminals do not treat CR and LF independently, and will have to |
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* go to some effort to simulate their effect. (For example, some |
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* terminals do not have a CR independent of the LF, but on such |
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* terminals it may be possible to simulate a CR by backspacing.) |
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* Therefore, the sequence "CR LF" must be treated as a single "new |
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* line" character and used whenever their combined action is |
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* intended; the sequence "CR NUL" must be used where a carriage |
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* return alone is actually desired; and the CR character must be |
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* avoided in other contexts. This rule gives assurance to systems |
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* which must decide whether to perform a "new line" function or a |
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* multiple-backspace that the TELNET stream contains a character |
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* following a CR that will allow a rational decision. |
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* |
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* Note that "CR LF" or "CR NUL" is required in both directions |
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* (in the default ASCII mode), to preserve the symmetry of the |
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* NVT model. Even though it may be known in some situations |
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* (e.g., with remote echo and suppress go ahead options in |
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* effect) that characters are not being sent to an actual |
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* printer, nonetheless, for the sake of consistency, the protocol |
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* requires that a NUL be inserted following a CR not followed by |
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* a LF in the data stream. The converse of this is that a NUL |
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* received in the data stream after a CR (in the absence of |
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* options negotiations which explicitly specify otherwise) should |
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* be stripped out prior to applying the NVT to local character |
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* set mapping. |
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* </pre> |
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* |
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* @author Jonathan Payne |
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*/ |
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public class TelnetOutputStream extends BufferedOutputStream { |
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boolean stickyCRLF = false; |
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boolean seenCR = false; |
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public boolean binaryMode = false; |
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public TelnetOutputStream(OutputStream fd, boolean binary) { |
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super(fd); |
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binaryMode = binary; |
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} |
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/** |
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* set the stickyCRLF flag. Tells whether the terminal considers CRLF as a single |
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* char. |
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* |
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* @param on the <code>boolean</code> to set the flag to. |
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*/ |
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public void setStickyCRLF(boolean on) { |
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stickyCRLF = on; |
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} |
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/** |
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* Writes the int to the stream and does CR LF processing if necessary. |
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*/ |
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public void write(int c) throws IOException { |
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if (binaryMode) { |
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super.write(c); |
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return; |
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} |
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if (seenCR) { |
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if (c != '\n') |
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super.write(0); |
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super.write(c); |
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if (c != '\r') |
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seenCR = false; |
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} else { // !seenCR |
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if (c == '\n') { |
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super.write('\r'); |
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super.write('\n'); |
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return; |
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} |
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if (c == '\r') { |
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if (stickyCRLF) |
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seenCR = true; |
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else { |
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super.write('\r'); |
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c = 0; |
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} |
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} |
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super.write(c); |
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} |
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} |
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/** |
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* Write the bytes at offset <i>off</i> in buffer <i>bytes</i> for |
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* <i>length</i> bytes. |
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*/ |
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public void write(byte bytes[], int off, int length) throws IOException { |
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if (binaryMode) { |
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super.write(bytes, off, length); |
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return; |
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} |
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while (--length >= 0) { |
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write(bytes[off++]); |
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} |
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} |
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} |